BOOK    58  1.D259   c.  1 

DARWIN    #    VARIOUS    CONTRIVANCES    BY 

WHICH    ORCHIDS    ARE    FERTILISED    BY    I 


3   T1S3   ODmnoi   1 


BRITI'LE  STC  RAGE 

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TUE  o/\ 

VARIOUS   CONTRIVANCES  \S>\2^ 


BY   WHICH 


ORCHIDS  ARE  FERTILISED  BY  INSECTS. 


By  CHAELES  DAKWIN,  M.A.,  F.R.S.,  &a 


SECOND  EDITION,  REVISED, 


WITH     ILLUSTRATIONS. 


l^EW  YOKK: 
D.    APPLETON    AND    COMPANY, 

1,    3,    AND    5   BOND    STREET. 
1892. 


^ 

-.M:^^ 


PREFACE 


THE    SECOND    EDITION. 


The  first  edition  of  this  work  was  published  early  in 
the  year  1862,  and  has  been  for  some  time  out  of  print. 
During  the  two  or  three  years  after  its  appearance 
I  received,  through  the  kindness  of  various  corre- 
spondents in  different  parts  of  the  world,  a  large 
uumber  of  letters,  especially  from  Fritz  Miiller  in  South 
Brazil,  communicating  to  me  many  new  and  curious 
facts,  and  calling  my  attention  to  some  errors.  Various 
memoirs  on  the  fertilisation  of  orchids  have  also  since 
been  published,  and  I  have  myself  examined  several 
new  and  striking  forms.  A  large  amount  of  matter 
has  thus  been  accumulated;  but  the  present  volume 
would  be  rendered  much  too  long  if  the  whole  were 
introdiiced.  I  have,  therefore,  selected  only  the  more 
interesting  facts,  and  have  given  a  brief  abstract  of 
the  several  published  papers.  The  work  has  thus  been 
remodelled ;  and  the  additions  and  corrections  are  so 
numerous  that  I  have  found  it  impossible  to  follow  my 
usual  plan  of  giving  a  list  of  them.     I  have,  however, 


n  PREFACE   TO   THE  SECOND  EDITION. 

appended,  in  chronological  order,  the  titles  of  all  the 
papers  and  books  on  the  fertilisation  of  the  Orchidese 
which  have  been  published  since  the  appearance  of 
the  first  edition  of  the  present  book.  Finally,  I  will 
remark  that  any  reader  who  wishes  merely  to  see  how 
wonderfully  complex  and  perfect  are  the  adaptations 
for  the  fertilisation  of  these  plants  had  better  read 
Chapter  VII.  on  the  Catasetidae.  The  account  of 
their  structure  and  of  the  action  of  the  several  parts 
will,  I  think,  be  intelligible,  if  he  will  first  glance  at 
the  explanation  of  the  terms  given  at  the  close  of 
the  Introduction. 


List  of  Pampers  and  Books  hearing  on  the  Fertilisation 
of  the  Orchidese,  which  have  been  published  since  the 
appearance  of  the  First  Edition  of  this  Worh  in 
1862,  arranged  in  Chronological  Order, 


Bronn,  H.  G. — *  Charles  Darwin,  iiber  die  Einriclitungen  zur  Be- 
fruchtimg  britischer  und  auslandischer  Orchideen.'  With 
an  Appendix  hy  the  Translator  on  Stanhopea  devoniensis. 
Stuttgart,  1862. 

Gray,  Asa. — On  Platanthera  {flahenaria)  and  Gymnadenia  in 
*  Enumeration  of  Plants  of  the  Rocky  Mountains.' — American 
Journal  of  Science  and  Arts,  Second  Series,  vol.  xxxiv.,  No. 
101,  Sept.  1862,  p.  33. 

Gray,  Asa. — On  Platanthera  hooJcert,  in  a  review  of  the  first  edi- 
tion of  the  present  work. — American  Journal  of  Science  and 
Arts,  vol.  xxxiv.  July  1862,  p.  143. 

Anderson,  J. — *  Fertilisation  of  Orchids.* — Journal  of  Horticulture 
and  Cottage  Gardener,  April  21,  1863,  p.  287. 

GossE,  P.  H. — *  Microscopic  Observation  on  some  Seeds  of  Orchids.' 
— Journal  of  Horticulture  and  Cottage  Gardener,  April  21, 
1863,  p.  287. 

Gray,  Asa. — On  Platanthera  (Hahernaria)  fiava  and  Gymnadenia 
tridentafa. — American  Journal  of  Science  and  Arts,  vol.  xxxvi. 
Sept.  1863,  p.  292. 

Journal  of  Horticulture  and  Cottage  Gardener. — March  17, 
1863,  p.  206.  '  On  Orchid  Cultivation,  Cross-breeding,  and 
Hybridising.* 

Scudder,  J.  H. — On  Pogonia  opMoglossoides.  Proceedings  of  the 
Boston  Society  of  Natural  Histoiy,  vol.  ix.  April,  1863. 

Tbeviranus. — 'Uebcr  Dichogamie  nach  C.  C.  Sprengel  und  Ch. 
Darwin.  §  3.  Orchideen.'— Botanische  Zeitung,  No.  2,  1863, 
p.  9. 


irm  LIST  OF  PAPERS  AND  BOOKS. 

Tbeviranus. — *  NachtrUgliche  Bemerkungen  tiber  die  Befruchtmig 
einiger  Orchideen.' — Botanische  Zeitung,  No.  32,  1863,  p. 
241. 

Tbimen,  E. — 'On  the  Fertilisation  of  JDisa  grandiflora,  Linn.' — 
Journal  of  Linnean  Society,  Botany,  vol.  vii.  1863,  p.  144. 

West  of  Scotland  Horticultural  Magazine. — '  Fertilisation  of 
Orchids,'  Sept.  1863,  p.  65. 

Ceuger. — *  A  few  Notes  on  the  Fecundation  of  Orchids,  and  their 
Morphology.' — Journal  of  Linnean  Society,  Botany,  vol.  viii. 
No.  31,  1864,  p.  127. 

Scott,  J. — '  On  the  Individual  Sterility  and  Cross-impregnation  of 
certain  Species  of  Oncidium.' — Journal  of  Linnean  Society, 
vol.  viii.  No.  31,  1864,  p.  162. 

MoGGRiDGE,  J.  Traherne. — '  Observations  on  some  Orchids  of  the 
South  of  France.' — Journal  of  Linnean  Society,  Botany,  vol. 
viii.  No.  32,  1865,  p.  256. 

Trimen,  R. — '  On  the  Structure  of  Bonatea  sjjeciosa,  Linn.,  with 
reference  to  its  Fertilisation.' — Journal  of  Linnean  Society, 
vol.  ix.  1865,  p.  156. 

EoHRBACH,  P. — ^'Ueber  Epipogium  gmelinV — Gekronte  Preisschrift, 
Gottingen,  1866. 

Delpino. — '  Sugli  Apparecchi  della  Fecondazione  nelle  Piante 
antocarpee.'     Florence,  1867. 

Hildebrand,  F. — '  Die  Geschlechter-Yertheilung  bei  den  Pflanzen,' 
&c.     Leipzig,  1867,  p.  51,  et  seq. 

Hildebrand,  F. — *  Frederigo  Delpino's  Beobachtungen  iiber  die 
Bestaubungsvorrichtungen  bei  den  Phanerogamen.' — Bota- 
nische Zeitung,  No.  34,  1867,  p.  265. 

MoGGRTDGE,  J.  Traherne,  ou  Ophrys. — 'Flora of  Mentone,'  1867  (?). 
Plates  43,  44,  45. 

Weale,  J.  P.  Mansel. — '  Notes  on  the  Structure  and  Fertilisation 
of  the  Genus  Bonatea,  with  a  special  description  of  a  Species 
found  at  Bedford,  South  Africa.' — Journal  of  Linnean  Society, 
Botany,  vol  x.  1867,  p.  470. 

Hildebrand. — 'Notizen  liber  die  Geschlechtsverhaltnisse  brasili- 
anischer  Pflanzen.  Aus  einem  Briefe  von  Fritz  Miiller.'— 
Botanische  Zeitung,  No.  8,  1868,  p.  113. 


LIST   OF   PAPERS   AND   BOOKS.  ix 

MtJLLEB,  Fritz. — *  Ueber  Befruchtungserscheimingeii  bei  OrcM- 
deen.'— Botaniscbe  Zeitung,  No.  39,  1868,  p.  629. 

MtJLLER,  Hermann. — '  Beobachtungen  an  westralishen  Orchideen.* 
— Yerhandlungen  des  nat.  Vereins  fiir  Pr.  Rheinl.  u.  Westf. 
1868  and  1869. 

Darwin,  Charles. — '  Notes  on  the  Fertilisation  of  Orchids.' — 
Annals  and  Magazine  of  Natural  History,  Sept.  1869. 

Delpino. — '  Ulterior!  Osservazioni  suUa  Dicogamia  nel  Regno  vege- 
tale.'    Parte  prima.     Milan,  1868-69,  pp.  175-78. 

MoGGBiDGE,  J.  Traherne. — *  UebeT  Ophrys  insectifera^  L.  (part). 
— Yerhandlungen  der  Kaiserl.  Leop.  Carol.  Akad.  (Nova 
Acta),  torn.  xxxv.  1869. 

MuLLER,    Fritz. —  *  Ueber    einige    Befruchtungserscheinungen.'— 


MiJLLEB,  Fritz. — *  Umwandlung  von  Staubgefassen  in  Stempel  bei 
Begonia.  Uebergang  von  Zwitterbliithigkeit  in  Getrenntblii- 
thigkeit  bei  Chamissoa.  Triandrische  Varietat  eines  monan- 
drischen  Epidendrum.' — Botanische  Zeitung,  No.  10,  1870, 
p.  149. 

Weale,  J.  P.  Mansel. — *  Note  on  a  Species  of  Disperis  found  on 
the  Kageberg,  South  Africa.' — Journal  of  Linnean  Society, 
Botany,  vol.  xiii.  1871,  p.  42. 

Weale,  J.  P.  Mansel. — *  Some  Observations  on  the  Fertilisation 
of  Disa  macrantha.' — Journal  of  Linnean  Society,  vol.  xiii. 
1871,  p.  45. 

Weale,  J.  P.  Mansel. — *  Notes  on  some  Species  of  Habenaria 
found  in  South  Africa.' — Journal  of  Linnean  Society,  vol  xiii. 
1871,  p.  47. 

Cheeseman,  T.  F. — *0n  the  Fertilisation  of  the  New  Zealand 
Species  of  Pterostylis.' — Transactions  of  the  New  Zealand  Insti- 
tute, vol.  V.  1873,  p.  352. 

Muller,  Hermann. — *  Die  Befruchtung  der  Blumen  durch  Insekten,* 
«fec.    Leipzig,  1873,  pp.  74-86. 

Cheeseman,  T.  F. — 'On  the  Fertilisation  of  Acianthus  cyrtostilis* 
— Transactions  of  the  New  Zealand  Institute,  vol.  vii.  1874 
(issued  1875),  p.  349. 


X  LIST  OF   PAPERS  AlH)  BOOKS. 

MtJLLEB,  Hermann. — 'Alpine  Orchids  adapted  to  Cross-fertilisation 
by  Butterflies/— Nature,  Dec.  31,  1874. 

Delpino. — *  Ulteriori    Osservazioni    sulla    Dicogamia    nel    Regno 
vegetale.'     Parte  seconda,  fasc.  ii.    Milan,  1875,  pp.  149,  150. 

Lubbock,  Sir  J. — '  British  Wild  Flowers.'  London,  1875,  pp.  162- 
175. 

Fitzgerald,  R.  D.— *  Australian  Orchids.'    Part  L  1875,  Part  II. 
1876.    Sydney,  New  South  Wales. 


CONTENTS. 


Introduction ..    Pages  1-5 

CHAPTER   I. 

OPHEE-ffl. 

Structure  of  the  flowex  of  Orcliis  mascula  —  Power  of  movement  of 
the  poUinia  —  Perfect  adaptation  of  the  parts  in  Orchis  pyra- 
midalis  —  Other  species  of  Orchis  and  of  some  closely  allied 
genera  —  On  the  insects  which  visit  the  several  species,  and  on 
the  frequency  of  their  visits  —  On  the  fertility  and  sterility  of 
various  Orchids  —  On  the  secretion  of  nectar,  and  on  insects 
being  purposely  delayed  in  obtaining  it 6-44 

CHAPTER   IL 

OPHRE^ — continued. 

Fly  and  Spider  Ophrys  —  Bee  Ophrys,  apparently  adapted  for 
perpetual  self-fertilisation,  but  with  paradoxical  contrivances  for 
intercrossing  —  Herminium  monorchis,  attachment  of  the  pol- 
linia  to  the  front  legs  of  insects — Peristylus  viridis,  fertilisation 
indirectly  effected  by  nectar  secreted  from  three  parts  of  the 
labellum — Gymnadenia  conopsea,  and  other  species — Habenaria 
or  Platanthera  chlorantha  and  bifolia,  their  pollinia  attached  to 
the  eyes  of  Lepidoptera — Other  species  of  Habenaria  —  Bonatea 
—  Disa  —  Summary  on  the  powers  of  movement  in  the  iwUinia 

45-79 


3U1  CONTENTS. 

CHAPTER   III. 

ARETHUSEJS. 

Cephalanthera  grandiflora ;  rostellum  aborted ;  early  penetration  of 
the  pollen-tabes ;  case  of  imperfect  self-fertilisation ;  cross- 
fertilisation  effected  by  insects  which  gnaw  the  labellum  — 
Cephalanthera  ensi  folia  —  Pogonia  —  Pterostylis  and  other 
Australian  orchids  with  the  labellum  sensitive  to  a  touch  — 
Vanilla  — Sobralia Pages  80-92 

CHAPTER   IV. 

NEOTTEiE. 

Epipactis  palustris ;  curious  shape  of  the  labellum  and  its  import- 
ance in  the  fructification  of  the  flower  —  other  species  of  Epi- 
pactis— Epipogium — Goodyera  repens — Spiranthes  autumnalis ; 
perfect  adaptation  by  which  the  pollen  of  a  younger  flower  is 
carried  to  the  stigma  of  an  older  flower  on  another  plant  — 
Listera  ovata ;  sensitiveness  of  the  rostellum ;  explosion  of 
viscid  matter;  action  of  insects;  perfect  adaptation  of  the 
several  organs  —  Listera  cordata  —  Neottia  nidus-avis;  its 
fertilisation  effected  in  the  same  manner  as  in  Listera — Thely- 
mitra,  self-fertile 93-127 

CHAPTER   V. 

MALAXEJB  AND   EPIDENDRE-ffiS. 

Malaxis  paludosa  —  Masdevallia,  curious  closed  flowers  —  Bolbo- 
phyllum,  labellum  kept  in  constant  movement  by  every  breath 
of  air  —  Dendrobium,  contrivance  for  self-fertilisation — Cattleya, 
simple  manner  of  fertilisation — Epidendrum — Self-fertile  Epi- 
dendreae        128-148 


CONTENTS.  XIU 

CHAPTER   VL 

YANDEX. 

Structure  of  the  column  and  pollinia  —  Importance  of  the  elasticity 
of  the  pedicel ;  its  power  of  movement  —  Elasticity  and  strength 
of  the  caudicles  —  Calanthe  with  lateral  stigmas,  manner  of 
fertilisation— Angr^cum  sesquipedale,  wonderful  length  of  nec- 
tary—  Species  with  the  entrance  into  the  stigmatic  chamhcr 
much  contracted,  so  that  the  pollen-masses  can  hardly  be 
inserted  —  Coryanthes,  extraordinary  manner  of  fertilisation 

Pages  149-177 


CHAPTER   YII. 

VANDEiE  continued. — catasetidje. 

Catasetida3,  the  most  remarkable  of  all  Orchids — The  mechanism 
by  which  the  pollinia  of  Catasetum  are  ejected  to  a  distance  and 
are  transported  by  insects  —  Sensitiveness  of  the  horns  of  the 
rostellum  —  Extraordinary  diflference  in  the  male,  female,  and 
hermaphrodite  forms  of  Catasetum  tridentatum  —  Mormodes 
ignea,  curious  structure  of  the  flowers ;  ejection  of  the  pollinia 
— Mormodes  luxata  —  Cycnoches  ventricosum,  manner  of  fer- 
tilisation             178-225 


CHAPTER   VIII. 

CYPRirEOEiE — HOMOLOGIES   OF   THE   FLOWERS  OF   ORCUIDB. 

Cypripedium,  differs  much  from  all  other  Orchids  —  Labellum  in 
the  form  of  a  slipper  with  two  small  orifices  by  which  insects 
can  escape — Manner  of  fertilisation  by  small  bees  of  the  genus 
Andrena — Homological  nature  of  the  several  parts  of  the  flowers 
of  the  Orchidese  —  "Wonderful  amount  of  modification  which 
they  have  undergone 226-246 


XIV  CONTENTS. 

CHAPTElt   IX. 

GBADATION    OF   OEGANS,   &C. CONCLUDING    EEMAKKS. 

Gradation  of  organs,  of  the  rostellum,  of  tlie  pollen-masses  — 
Formation  of  the  caudicle  —  Genealogical  affinities  —  Secretion 
of  nectar — Mechanism  of  the  movement  of  the  poUinia  —  Uses 
of  the  petals  —  Production  of  seed  —  Importance  of  trifling 
details  of  structure  —  Cause  of  the  great  diversity  of  structure  in 
the  flowers  of  Orchids — Cause  of  the  perfection  of  the  con- 
trivances —  Summary  on  insect-agency  —  Nature  abhors  per- 
petual self-fertilisation  Page  247-293 


Index 294 


LIST   OF   WOODCUTS. 


PAOS 

1.  Oechis  mascula 8 

2.  „           „       pollinia  of 12 

3.  Orchis  pyramidalis 18 

4.  Moth's  head  and  proboscis,  with  attached  pollinia  31^ 

5.  Ophrts  muscifeea 46 

6.  „        aeanifera 50 

7.  „        arachnites 51 

8.  „           APIFERA 53 

9.  Peristylus  viridis 62 

10.  Gymnadenia  conopsea      65 

11.  Habenaria  chlorantha 69 

12.  Pollinia  of  habenarla  chlorantha  and  bifolia   ..  74 

13.  Cephalanthera  grandiflora         81 

14.  Pterostylis  longifolia 87 

15.  Epipactis  palustris 94 

16.  „          latifolla. 101 

17.  Spiranthes  autumnalis 107 

18.  LiSTERA  ovata 116 

19.  Malaxis  paludosa 130 

20.  Masdevallia  fenestrata       136 

21.  Dendrobium  chrysanthum      139 

22.  Cattleya 144 

23.  Diagram   illustrative   of  the    structure   of    the 

Yandex      150 

24.  Pollinia  of  YANDEiE       154 

25.  PoLLiNiuM  of  Ornithocephalus 160 


XVI  LIST  OF  WOODCUTS. 

PAOB 

26.  Calanthe  masuca     161 

27.  coryanthes  speciosa       174 

vCatasetum  saccatum •j 

30.  CaTASETUM  TRIDENT atum            194 

31.  Monachanthus  and  Myanthus 199 

32.  Mormodes  ignea        209 

33.  Cycnoches  ventricosum 222 

34.  •  „                    „           section  through  bud  ..      ..  223 

35.  Cypripedium       ?27 

36.  Transverse  section  of  flower  of  an  Orchid          ..  236 

37.  EosTELLUM  OF  Catasetum       256 

38.  Disc  of  Gymnadenia  conopsea      272 


P.  S. — I  am  much  indebted  to  Mr.  G.  B.  Sowerby  for  the  pains 
wbich  he  has  taken  in  making  the  Diagrams  as  intelligible  as 


ON  THE 

FERTILISxiTION  OF  ORCHIDS 

BY 

INSECTS, 

&c.  &c. 


INTKODUCTION. 

The  object  of  the  following  work  is  to  show  that  the 
contrivances  by  which  Orchids  are  fertilised,  are  as 
varied  and  almost  as  perfect  as  any  of  the  most  beauti- 
ful adaptations  in  the  animal  kingdom  ;  and,  secondly, 
to  show  that  these  contrivances  have  for  their  main 
object  the  fertilisation  of  the  flowers  with  pollen 
brought  by  insects  from  a  distinct  plant.  In  my 
volume  *  On  the  Origin  of  Species '  I  gave  only  general 
reasons  for  the  belief  that  it  is  an  almost  universal  law 
of  nature  that  the  higher  organic  beings  require  an 
occasional  cross  with  another  individual ;  or,  which  is 
the  same  thing,  that  no  hermaphrodite  fertilises  itself 
for  a  perpetuity  of  generations.  Having  been  blamed 
for  propounding  this  doctrine  without  giving  ample 
facts,  for  which  I  had  not  sufficient  space  in  that  work, 
I  wish  here  to  show  that  I  have  not  spoken  without 
having  gone  into  details. 

I  have  been  led  to  publish  this  little  treatise  sepa- 
rately, as  it  is  too  large  to  be  incorporated  with  any 
other  subject.  As  Orchids  are  universally  acknow- 
ledged to  rank  amongst  the  most  singular  and  most 


^  INTRODUCTION. 

modified  forms  in  the  vegetable  kingdom,  I  have 
thought  that  the  facts  to  be  given  might  lead  some 
observers  to  look  more  curiously  into  the  habits  of  our 
several  native  species.  An  examination  of  their  many- 
beautiful  contrivances  will  exalt  the  whole  vegetable 
kingdom  in  most  persons'  estimation.  I  fear,  however, 
that  the  necessary  details  are  too  minute  and  complex 
for  any  one  who  has  not  a  strong  taste  for  Natural 
History.  This  treatise  affords  me  also  an  opportunity 
of  attempting  to  show  that  the  study  of  organic  beings 
may  be  as  interesting  to  an  observer  who  is  fully  con- 
vinced that  the  structure  of  each  is  due  to  secondary 
laws,  as  to  one  who  views  every  trifling  detail  of 
structure  as  the  result  of  the  direct  interposition  of  the 
Creator. 

I  must  premise  that  Christian  Konrad  Sprengel,  in 
his  curious  and  valuable  work,  *  Das  entdeckte  Geheim- 
niss  der  Natur,'  published  in  1793,  gave  an  excellent 
outline  of  the  action  of  the  several  parts  in  the  genus 
Orchis ;  for  he  well  knew  the  position  of  the  stigma, 
and  he  discovered  that  insects  were  necessary  to  remove 
the  pollen-masses.*  But  he  overlooked  many  curious 
contrivances, — a  consequence,  apparently,  of  his  belief 
that  the  stigma  generally  receives  pollen  from  the 
same  flower.  Sprengel,  likewise,  has  partially  described 
the  structure  of  Epipactis ;  but  in  the  case  of  Listera 
he  entirely  misunderstood  the  remarkable  phenomena 
characteristic  of  that  genus,  which  has  been  well  de- 
scribed by  Dr.  Hooker  in  the  'Philosophical   Trans- 


*  Delpino  has  found  ('  Ult.  Os-  In   this  memoir   Waetchf  r,  who 

Borvazioui  sulla  Dicogamia,'  Part  does  not  seem   to  have  been  ac- 

ii.  1875,  p.  loOj  amemoir  by  Waet-  quainted   with   Spiengel's  work, 

cher,  published  in  1801    in  Roe-  sliows  that  insects  aie  necessary 

mer's  '  Archiv  fUr  die  Botanik.'  t.  for    the   fertilisation    of    various 

ii.  p.  11,  which  apparently  has  re-  orchids,   and   describes  well  the 

ixiained  unknown  to  everyone  else.  wonderful  structure  of  Neottia. 


INTRODUCTION.  3 

actions'  for  1854.  Dr.  Hooker  has  given  a  full  and 
accurate  account,  with  drawings,  of  the  structure  of 
the  parts  ;  but  from  not  having  attended  to  the  agency 
of  insects,  he  did  not  fully  understand  the  object 
gained.  Robert  Brown,*  in  his  celebrated  paper  in  the 
*  Linnean  Transactions,*  expresses  his  belief  that  insects 
are  necessary  for  the  fructification  of  most  Orchids; 
but  adds,  that  the  fact  of  all  the  capsules  on  a  dense 
spike  not  infrequently  producing  seed,  seems  hardly 
reconcilable  with  this  belief:  we  shall  hereafter  find 
that  this  doubt  is  groundless.  Many  other  authors 
have  given  facts  and  expressed  their  belief,  more  or 
less  fully,  on  the  necessity  of  insect-agency  in  the 
fertilisation  of  Orchids. 

In  the  course  of  the  following  work  I  shall  have  the 
pleasure  of  expressing  my  deep  obligation  to  several 
gentlemen  for  their  unremitting  kindness  in  sending 
me  fresh  specimens,  without  which  aid  this  work  would 
have  been  impossible.  The  trouble  which  several  of 
my  kind  assistants  have  taken  has  been  extraordinary : 
I  have  never  once  expressed  a  wish  for  aid  or  for  in- 
formation which  has  not  been  granted  me,  as  far  as 
possible,  in  the  most  liberal  spirit. 

EXPLANATION   OF   TERMS. 

In  case  any  one  should  look  at  this  treatise  who  has 
never  attended  to  Botany,  it  may  be  convenient  to 
explain  the  meaning  of  the  common  terms  used.  In 
most  flowers  the  stamens,  or  male  organs,  surround  in 
a  ring  the  one  or  more  female  organs,  called  the  pistils. 
In  all  common  Orchids  there  is  only  one  well-developed 
stamen,  which  is  confluent  with  the  pistils,  and  they 


Linnean  Transactions,'  1833,  vol,  xvi.  p.  704. 


4  INTRODUCTION. 

form  together  the  column.  Ordinary  stamens  consist 
of  a  filament,  or  supporting  thread  (rarely  seen  in 
British  Orchids),  which  carries  the  anther ;  and  within 
the  anther  lies  the  pollen  or  male  vivifying  element. 
The  anther  is  divided  into  two  cells,  which  are  very 
distinct  in  most  Orchids,  so  much  so  as  to  appear  in 
some  species  like  two  separate  anthers.  The  pollen  in 
all  common  plants  consists  of  fine  granular  powder: 
but  in  most  Orchids  the  grains  cohere  in  masses,  which 
are  often  supported  by  a  very  curious  appendage,  called 
the  caudicle.  This  part  and  all  the  other  organs  will 
hereafter  be  more  fully  described  and  figured  under  the 
head  of  the  first  species.  Orchis  mascula.  The  pollen- 
masses,  with  their  caudicles  and  other  appendages,  are 
called  the  polUnia. 

Orchids  properly  have  three  pistils  or  female  organs, 
united  together,  the  upper  and  anterior  surfaces  of  two 
of  which  form  the  two  stigmas.  But  the  two  are  often 
completely  confluent,  so  as  to  appear  as  one.  The 
stigma  is  penetrated  in  the  act  of  fertilisation  by  long 
tubes,  emitted  by  the  pollen-grains,  which  carry  the 
contents  of  the  grains  down  to  the  ovules  or  young 
seeds  in  the  ovarium. 

The  upper  stigma  is  modified  into  an  extraordinary 
organ,  called  the  rostellum,  which  in  many  Orchids 
presents  no  resemblance  to  a  true  stigma.  When 
mature  it  either  includes  or  is  altogether  formed  of 
viscid  matter.  In  many  species  the  pollen-masses  are 
firmly  attached  to  a  portion  of  the  exterior  membrane, 
which,  when  insects  visit  the  flowers,  is  removed, 
together  with  the  pollen-masses.  This  removable 
portion  consists  in  most  British  Orchids  merely  of  a 
small  piece  of  membrane,  with  a  layer  or  ball  of  viscid 
matter  underneath,  and  I  shall  call  it  the  "  viscid  disc;" 
but  in  many  exotic  species  the  portion  removed  is  so 


INTRODUCTION.  O 

large  and  so  important,  tliat  one  part  must  be  called, 
as  before,  the  viscid  disc,  and  the  other  part  the  pedicel 
of  the  rostellum,  to  the  end  of  which  the  pollen-masses 
are  attached.  Authors  have  called  that  portion  of  the 
rostellum  which  is  removed,  the  "  gland  "  or  "  retina- 
culum," from  its  apparent  function  of  retaining  the 
pollen-masses  in  their  places.  The  pedicel,  or  pro- 
longation of  the  rostellum,  to  which  in  many  exotic 
species  the  pollen-masses  are  attached,  seems  generally 
to  have  been  confounded,  under  the  name  of  caudicle, 
with  the  true  caudicle  of  the  pollen-masses,  though 
their  nature  and  origin  are  totally  different.  The  part 
of  the  rostellum  which  is  left  after  the  removal  of 
the  discs  and  viscid  matter,  is  sometimes  called  the 
"  bursicula,"  or  "  fovea,"  or  "  pouch."  But  it  will  be 
found  convenient  to  avoid  all  these  terms,  and  to  call 
the  whole  modified  stigma  the  rostellum — sometimes 
adding  an  adjective  to  define  its  shape ;  that  portion 
of  the  rostellum  which  is  removed  with  the  pollen- 
masses  being  called  the  viscid  disc,  together  in  some 
cases  with  the  pedicel. 

Lastly,  the  three  outer  divisions  of  the  flower  are 
called  sepals,  and  form  the  calyx ;  but,  instead  of  being 
green,  as  in  most  common  flowers,  they  are  generally 
coloured,  like  the  three  inner  divisions  or  2^etals  of  the 
flower.  In  almost  all  the  species,  one  of  the  petals, 
which  is  properly  the  upper  one,  is  larger  than  the 
others  and  stands  on  the  lower  side  of  the  flower,  where 
it  offers  a  landing-place  for  insects,  having  been  carried 
round  by  the  twisting  of  the  ovarium.  It  is  called 
the  lower  lip  or  Idbellum,  and  often  assumes  most 
singular  shapes.  It  secretes  nectar  for  the  sake  of 
attracting  insects,  and  is  often  produced  into  a  spur- 
like nectary. 


OPHRE^.  Chap.  I. 


CHAPTER  I. 

OPHEE^. 

Structure  of  the  flower  of  Orchis  mascula — Power  of  movement  of  the 
pollinia — Perfect  adaptation  of  the  parts  in  Orchis  pyramidalis — 
Other  species  of  Orchis  and  of  some  closely  allied  genera — On  the 
insects  which  visit  the  several  species,  and  on  the  frequency  of  their 
visits — On  the  fertility  and  sterility  of  various  Orchids — On  the 
secretion  of  nectar  and  on  insects  being  purposely  delayed  in 
obtaining  it. 

Theoughout  the  following  volume  I  have  followed,  as 
far  as  I  conveniently  could,  the  arrangement  of  the 
OrchidesB  given  by  Lindley.  The  British  species 
belong  to  five  of  his  tribes,  the  Ophrese,  Neotteee, 
Arethusese,  MalaxeaB  and  Cypripedese,  but  the  two 
latter  tribes  contain  each  only  a  single  genus.  Various 
British  and  foreign  species  belonging  to  the  several 
tribes  are  described  in  the  first  eight  chapters.  The 
eighth  also  contains  a  discussion  on  the  homologies  of 
the  flowers  of  the  Orchideae.  The  ninth  chapter  is 
devoted  to  miscellaneous  and  general  considerations.  • 
The  Ophrete  include  most  of  our  common  British 
species,  and  we  will  begin  with  the  genus  Orchis.  The 
reader  may  find  the  following  details  rather  difficult 
to  understand ;  but  I  can  assure  him,  if  he  will  have 
patience  to  make  out  the  first  case,  the  succeeding  ones 
will  be  easily  intelligible.  The  accompanying  diagrams 
(fig.  1,  p.  8)  show  the  relative  position  of  the  more 
important  organs  in  the  flower  of  the  Early  Orchis 
(0.  mascula).  The  sepals  and  the  petals  have  been  re- 
moved, excepting  the  labellum  with  its  nectary.     The 


CiiAP.  I.  ORCHIS   MASCULA.  i 

nectary  is  shown  only  in  the  side  view  (ti,  fig.  A) ; 
for  its  enlarged  orifice  is  almost  hidden  in  shade  in  the 
front  view  (B).  The  stigma  (s)  is  bilobed,  and  con- 
sists of  two  almost  confluent  stigmas  ;  it  lies  under  the 
pouch-formed  rostellum  (r).  The  anther  (a,  in  B  and 
A)  consists  of  two  rather  widely  separated  cells,  which 
are  longitudinally  open  in  front :  each  cell  includes  a 
pollen-mass  or  pollinium. 

A  pollinium  removed  out  of  one  of  the  two  anther- 
cells  is  represented  by  fig.  C  ;  it  consists  of  a  number 
of  wedge-formed  packets  of  pollen-grains  (see  fig.  F, 
in  which  the  packets  are  forcibly  separated),  united 
together  by  excessively  elastic,  thin  threads.  These 
threads  become  confluent  at  the  lower  end  of  each 
pollen-mass,  and  compose  the  straight  elastic  caudicle 
(c,  C).  The  end  of  the  caudicle  is  firmly  attached  to 
the  viscid  disc  {d,  C),  which  consists  (as  may  be  seen 
in  the  section  of  the  pouch-formed  rostellum,  fig.  E) 
of  a  minute  oval  piece  of  membrane,  with  a  ball  of 
viscid  matter  on  its  under  side.  Each  pollinium  has 
its  separate  disc ;  and  the  two  balls  of  viscid  matter 
lie  enclosed  together  (fig.  D)  within  the  rostellum. 

The  rostellum  is  a  nearly  spherical,  somewhat 
pointed  projection  (r,  figs.  A  and  B)  overhanging  the 
two  almost  confluent  stigmas,  and  must  be  fully  de- 
scribed, as  every  detail  of  its  structure  is  full  of  signi- 
ficance. A  section  through  one  of  the  discs  and  balls 
of  viscid  matter  is  given  (fig.  E) ;  and  a  front  view  of 
both  viscid  dies  within  the  rostellum  (fig.  D)  is  like- 
wise given.  This  latter  figure  (D)  probably  best 
serves  to  explain  the  structure  of  the  rostellum ;  but 
it  must  be  understood  that  the  front  lip  is  here  con- 
siderably depressed.  The  lowest  part  of  the  anther  is 
united  to  the  back  of  the  rostellum,  as  may  be  seen 
in  fig.  B.     At  an  early  period  of  growth  the  rostellum 


OPHKE^. 


Chap.  I. 


Fig.  1. 


Oechis  mascula 


Chap.  I.  ORCHIS  MASCULA.  9 


Desceiption  of  Fig.  1. 


a.  anther,  consisting  of  two  cells. 
r.  rostellum. 
s.  stigma. 
Z.  labellum. 


n.  nectary. 
p.  pollen-mass. 

c.  caudicle  of  poUinium. 

d.  viscid  disc  of  pollinium. 


A.  Side  view  of  flower,  with  all  the  petals  and  sepals  cut  off  except  the 

labellum,  of  which  the  near  half  is  cut  away,  as  well  as  the  upper 
portion  of  the  near  side  of  the  nectary. 

B.  Front  view  of  flower,  with  all  sepals  and  petals  removed,  except  the 

labellum. 

C.  One  pollinium,  showing  the  packets  of  pollen-grains,  the  caudicle,  and 

viscid  disc. 

D.  Front  view  of  the  caudicles  of  both  pollinia  with  the  discs  lying  within 

the  rostellum,  its  lip  being  depressed. 

E.  Section  through  one  side  of  the  rostellum,  with  the  included  disc  and 

caudicle  of  one  pollinium,  lip  not  depressed. 

F.  Packets  of  pollen-grains,  tied  together  by  clastic  threads,  here  eztcudcfl. 

(Copied  from  Bauer.) 


)U  OPHEE^.  Chap.  I. 

consists  of  a  mass  of  polygonal  cells,  full  of  brownish 
matter,  which  cells  soon  resolve  themselves  into  two 
balls  of  extremely  viscid  semi-fluid  matter,  void  of 
structure.  These  viscid  masses  are  slightly  elongated, 
almost  flat  on  the  top,  and  convex  below.  They  lie 
quite  free  within  the  rostellum  (being  surrounded  by 
fluid),  except  at  the  back,  where  each  viscid  ball 
adheres  to  a  small  portion  or  disc  of  the  exterior 
membrane  of  the  rostellum.  The  ends  of  the  two 
caudicles  are  strongly  attached  externally  to  these 
two  little  discs  of  membrane. 

The  membrane  forming  the  whole  exterior  surface 
of  the  rostellum  is  at  first  continuous ;  but  as  soon  as 
the  flower  opens  the  slightest  touch  causes  it  to  rupture 
transversely  in  a  sinuous  line,  in  front  of  the  anther- 
cells  and  of  the  little  crest  or  fold  of  membrane  (see 
fig.  D)  between  them.  This  act  of  rupturing  makes 
no  difference  in  the  shape  of  the  rostellum,  but  con- 
verts the  front  part  into  a  lip,  which  can  be  depressed 
easily.  This  lip  is  represented  considerably  depressed 
in  fig.  D,  and  i^s  edge  is  seen,  fig.  B,  in  the  front  view. 
When  the  lip  is  thoroughly  depressed,  the  two  balls 
of  viscid  matter  are  exposed.  Owing  to  the  elasticity 
of  the  hinder  part,  the  lip  or  pouch,  after  being 
pressed  down,  springs  up  again  and  encloses  the  two 
viscid  balls. 

I  will  not  affirm  that  the  rupturing  of  the  exterior 
membrane  of  the  rostellum  never  takes  place  sponta- 
neously ;  and  no  doubt  the  membrane  is  prepared  for 
rupture  by  having  become  very  weak  along  defined 
lines ;  but  several  times  I  saw  the  act  ensue  from  an 
excessively  slight  touch — so  slight  that  I  conclude 
that  the  action  is  not  simply  mechanical,  but,  for  the 
want  of  a  better  term,  may  be  called  vital.  We  shall 
hereafter  meet  with  other  cases,  in  which  the  slightest 


Chap.  I.  ORCHIS   MASCULA.  11 

touch  or  the  vapour  of  chloroform  causes  the  exterior 
membrane  of  the  rostellum  to  rupture  along  certain 
defined  lines. 

At  the  same  time  that  the  rostellum  becomes  trans- 
versely ruptured  in  front,  it  probably  (for  it  was 
impossible  to  ascertain  this  fact  from  the  position  of 
the  parts)  ruptures  behind  in  two  oval  lines,  thus 
separating  and  freeing  from  the  rest  of  the  exterior 
surface  of  the  rostellum  the  two  little  discs  of  mem- 
brane, to  which  the  two  caudicles  are  attached  exter- 
nally, and  to  which  the  two  balls  of  viscid  matter 
adhere  internally.  The  line  of  rupture  is  thus  very 
complex,  but  strictly  defined. 

As  the  two  anther-cells  are  open  longitudinally 
in  front  from  top  to  bottom,  even  before  the  flower 
expands,  it  follows  that  as  soon  as  the  rostellum  is 
properly  ruptured  from  the  effects  of  a  slight  touch, 
its  lip  can  be  depressed  easily,  and,  the  two  little  discs 
of  membrane  being  already  separate,  the  two  pollinia 
now  lie  absolutely  free,  but  are  still  embedded  in  their 
proper  places.  So  that  the  packets  of  pollen  and  the 
caudicles  still  lie  within  the  anther-cells ;  the  discs 
still  form  part  of  the  rostellum,  but  are  separate  ;  and 
the  balls  of  viscid  matter  still  lie  concealed  within 
the  rostellum. 

Now  let  us  see  in  the  case  of  Orchis  maseula  (fig.  1) 
how  this  complex  mechanism  acts.  Suppose  an  insect 
to  alight  on  the  labellum,  which  forms  a  good  landing- 
place,  and  to  push  its  head  into  the  chamber  (see  side 
view,  A,  or  front  view,  B),  at  the  back  of  which  lies  the 
stigma  (s),  in  order  to  reach  with  its  proboscis  the  end 
of  the  nectary ;  or,  which  does  equally  well  to  show 
the  action,  push  very  gently  a  sharply-pointed  common 
pencil  into  the  nectary.  Owing  to  the  pouch-formed 
rostellum  projecting  into  the  gangway  of  the  nectary, 


12  OPHRE^.  Chap.  I. 

it  is  scarcely  possible  that  any  object  can  be  pushed 
into  it  without  the  rostellum  being  touched.  The  ex- 
terior membrane  of  the  rostellum  then  ruptures  in  the 
proper  lines,  and  the  lip  or  pouch  is  easily  depressed. 
When  this  is  effected,  one  or  both  of  the  viscid  balls 
will  almost  infallibly  touch  the  intruding  body.  So 
viscid  are  these  balls  that  whatever  they  touch  they 
firmly  stick  to.  Moreover  the  viscid  matter  has 
the  peculiar  chemical  quality  of  setting,  like  a 
cement,  hard  and  dry  in  a  few  minutes'  time.  As  the 
anther-cells  are  open  in  front,  when  the  insect  with- 
draws its  head,  or  when  the  pencil  is  withdrawn,  one 
pollinium,  or  both,  will  be  withdrawn,  firmly  cemented 
to  the  object,  projecting  up  like  horns,  as  shown  (fig.  2) 

Fiff.  2. 


A.  Pollen-mass  of  0.  mascula,  when    I    B.  Pollen-mass  of  0.  mascula,  after 
first  attached.  |  the  act  of  depression. 

by  the  upper  figure,  A.  The  firmness  of  the  attach- 
ment of  the  cement  is  very  necessary,  for  if  the 
pollinia  were  to  fall  sideways  or  backwards  they  could 
never  fertilise  the  flower.  From  the  position  in 
which  the  two  pollinia  lie  in  their  cells,  they  diverge  a 
little  when  attached  to  any  object.  Now  suppose  that 
the  insect  flies  to  another  flower,  or  let  us  insert  the 
pencil  (A,  fig.  2),  with  the  attached  pollinium,  into 


CuAP.  I.  ORCHIS   MASCULA.  13 

the  same  or  into  another  nectary :  by  looking  at  the 
diagram  (fig.  1,  A)  it  will  be  evident  that  the  firmly 
attached  pollinium  will  be  simply  pushed  against  or 
into  its  old  position,  namely,  into  the  anther-cell. 
How  then  can  the  flower  be  fertilised?  This  is 
effected  by  a  beautiful  contrivance :  though  the  viscid 
surface  remains  immovably  affixed,  the  apparently 
insignificant  and  minute  disc  of  membrane  to  which  the 
caudicle  adheres  is  endowed  with  a  remarkable  power 
of  contraction  (as  will  hereafter  be  more  minutely 
described),  which  causes  the  pollinium  to  sweep 
through  an  angle  of  about  ninety  degrees,  always  in 
one  direction,  viz.,  towards  the  apex  of  the  proboscis  or 
pencil,  in  the  course  of  thirty  seconds  on  an  average. 
The  position  of  the  pollinium  after  the  movement  is 
shown  at  B  in  fig.  2.  After  this  movement,  completed 
in  an  interval  of  time  which  would  allow  an  insect  to 
fly  to  another  plant,*  it  will  be  seen,  by  turning  to  the 
diagram  (fig.  1,  A),  that,  if  the  pencil  be  inserted  into 
the  nectary,  the  thick  end  of  the  pollinium  now 
exactly  strikes  the  stigmatic  surface. 

Here  again  comes  into  play  another  pretty  adapta- 
tion, long  ago  noticed  by  Eobert  Brown.f  The 
stigma  is  very  viscid,  but  not  so  viscid  as  when 
touched  by  a  pollinium  to  pull  the  whole  off  an  insect's 
head  or  off  a  pencil,  yet  sufficiently  viscid  to  break 
the  elastic  threads  (fig.  1,  F)  by  which  the  packets 
of  pollen-grains  are  tied  together,  and  leave  some  of 
them  on  the  stigma.  Hence  a  pollinium  attached  to 
an  insect  or  to  a  pencil  can  be  applied  to  many 
stigmas,  and  will  fertilise  all.     I  have  often  seen  the 


*  Dr.  H.  Miiller  ('Die  Befruch-  flowers    of   Orchis  mancula,   and 

tuns;  der  Blumen  durch  lusekten,*  finds  that  this  t^tatement  is  correct. 

IS73,  p.  84)  has  timed  humble-  f  '  Transactions  of  the  Linnean 

bees   at   work  on   the   spikes   of  Society,'  vol.  xvi.  p.  731. 


14  OPHEE^.  Chap.  L 

poUinia  of  Orchis  pjramidalis  adhering  to  the  pro- 
boscis of  a  moth,  with  the  stump-like  caudicles  alone 
left,  all  the  packets  of  pollen  having  been  left  glued 
to  the  stigmas  of  the  successively  visited  flowers. 

One  or  two  other  little  points  must  be  noticed. 
The  balls  of  viscid  matter  within  the  pouch-formed 
rostellum  are  surrounded  with  fluid ;  and  this  is 
very  important,  for,  as  already  mentioned,  the  viscid 
matter  sets  hard  when  exposed  to  the  air  for  a  very 
short  time.  I  have  pulled  the  balls  out  of  their 
pouches,  and  found  that  they  had  entirely  lost  the 
power  of  adhesion  after  a  few  minutes.  Again,  the 
little  discs  of  membrane,  the  movement  of  which,  as 
causing  the  movement  of  the  poUinia,  is  so  abso- 
lutely indispensable  for  the  fertilisation  of  the  flower, 
lie  at  the  upper  and  back  surface  of  the  rostellum, 
and  are  closely  enfolded  and  thus  kept  damp  within 
the  bases  of  the  anther-cells  ;  and  this  is  very  neces- 
sary, as  an  exposure  of  about  thirty  seconds  causes 
the  movement  of  depression  to  take  place  ;  but  as 
long  as  the  disc  is  kept  damp,  the  pollinia  remain 
ready  for  action  whenever  removed  by  an  insect. 

Lastly,  as  I  have  shown,  the  pouch,  after  being 
depressed,  springs  up  to  its  former  position ;  and  this 
is  likewise  of  great  service ;  for  if  this  action  did  not 
take  place,  and  an  insect  after  depressing  the  lip 
failed  to  remove  the  two  viscid  balls,  or  if  it  removed 
one  alone,  then  in  the  first  case  both,  and  in  the 
second  case  one  would  be  left  exposed  to  the  air; 
consequently  one  or  both  would  quickly  lose  all 
adhesiveness,  and  the  pollinium  would  be  rendered  ab- 
solutely useless.  That  with  many  kinds  of  Orchids 
insects  often  remove  only  one  of  the  two  pollinia  at 
a  time  is  certain;  it  is  even  probable  that  they 
generally  remove  only  one,  for  the  lower   and  older 


Chap.  L  ORCHIS,  15 

flowers  almost  always  have  both  poUinia  remoyed, 
whilst  the  younger  flowers  close  beneath  the  buds, 
which  will  have  been  seldomer  visited,  have  frequently 
only  one  poUinium  removed.  In  a  spike  of  Orchis 
macidata,  I  found  as  many  as  ten  flowers,  chiefly  the 
upper  ones,  ^\  hich  had  only  one  pollinium  removed ; 
the  other  pollinium  being  still  in  its  proper  place  with 
the  lip  of  the  rostellum  well  closed  up  ;  so  that  all  the 
mechanism  was  perfect  for  its  subsequent  removal  by 
gome  other  insect. 

When  the  first  edition  of  this  book  was  published, 
I  had  not  seen  any  insects  visiting  the  flowers  of 
the  present  species  ;  but  a  friend  watched  some  plants, 
•^nd  saw  them  visited  by  several  humble-bees,  appa- 
rently Bomhus  muscorum  ;  and  Dr.  H.  Miiller  *  has  seen 
four  other  species  of  Bombus  at  work.  He  caught 
ninety-seven  specimens,  and  of  these  thirty-two  had 
pollinia  attached  to  their  heads. 

The  description  now  given  of  the  action  of  the 
organs  in  Orchis  mascula  applies  to  0,  morio,  fusca, 
macvlata,  and  latifdia.  These  species  present  slight 
and  apparently  co-ordinated  differences  in  the  length 
of  their  caudicles,  in  the  direction  of  the  nectary, 
in  the  shape  and  position  of  the  stigma,  but  they 
are  not  worth  detailing.  In  all,  the  pollinia  when 
removed  from  the  anther-cells  undergo  the  curious 
movement  of  depression,  which  is  so  necessary  to 
place  them  in  a  right  position  on  an  insect's  head 
for  striking  the  stigmatic  surface  of  another  flower. 
Six  species  of  humble-bees,  the  hive-bee  and  two 
other  kinds  have  been  seen  by  H.  Miiller  and  myself 
risitiug  the  flowers  of  Orchis  morio.     On  some  of  the 


*  '  Die  Befruchtung,  &c.,  p.  84. 


16  OPHRE^.  Chap.  L 

hive -bees  from  ten  to  sixteen  pollen -masses  adhered ; 
to  the  head  of  Eucera  longicornis  eleven,  to  the  head  of 
Osmia  rufa  several,  and  several  to  the  bare  surface  close 
above  the  mandibles  of  Bomhus  muscorum.  H.  Miiller 
has  seen  twelve  different  kinds  of  bees  visiting  the 
flowers  of  0.  latifolia,  which  are  also  visited  by 
Diptera.  My  son  George  observed  for  some  time 
plants  of  0.  maculata^  and  saw  many  specimens  of  a 
fly  (Empis  livida)  inserting  their  proboscides  into  the 
nectary ;  and  subsequently  the  same  fact  was  ob- 
served by  me.  He  brought  home  six  specimens  of  this 
Empis,  with  pollinia  attached  to  their  spherical  eyes, 
on  a  level  with  the  bases  of  the  antennae.  The  pollinia 
had  undergone  the  movement  of  depression,  and  stood 
a  little  above  and  parallel  to  the  proboscis  :  hence 
they  were  in  a  position  excellently  adapted  to  strike 
the  stigma.  Six  pollinia  were  thus  attached  to  one 
specimen,  and  three  to  another.  My  son  also  saw 
another  and  smaller  species  {Empis  pennipes)  inserting 
its  proboscis  into  the  nectary;  but  this  species  did 
not  act  so  well  or  so  regularly  as  the  other  in 
fertilising  the  flowers.  One  specimen  of  this  latter 
Empis  had  five  pollinia,  and  a  second  had  three 
pollinia,  attached  to  the  dorsal  surface  of  its  convex 
thorax.  H.  Miiller  has  seen  two  other  genera  of 
Diptera  at  work  on  this  orchis,  with  pollinia  attached 
to  the  front  part  of  their  bodies ;  and  on  one  occasion 
he  saw  a  humble-bee  visiting  the  flowers.* 

We   now   come  to  Orchis    (sub-genus,  Anacamptis) 
pi/ramidalis,  one  of  the  most  highly  organised  species 

*    M.     M.    Girard    caught    a  front  of  its  mouth  :  'Aunalea  de 

lougicorn  beetle,  Stranyalia  atra,  la   Soc.   Eutomolog.   de   France,* 

with  a  tuft  of  the  pollen-masses  torn  ix.  1869,  p.  xxxi. 
of  this   orchis  attached   to   the 


Chap.  I.  OECHIS   PYEAMIDALIS.  17 

which  I  have  examined,  and  which  is  ranked  by  several 
botanists  as  a  distinct  genus.  The  relative  position  of 
the  parts  (fig.  3)  is  here  considerably  different  from 
what  it  is  in  0.  mascula  and  its  allies.  There  are  two 
quite  distinct  rounded  stigmatic  surfaces  (s,  s,  A) 
placed  on  each  side  of  the  pouch-formed  rostellum. 
This  latter  organ,  instead  of  standing  some  height 
above  the  nectary,  is  brought  down  (see  side  view  B) 
so  as  to  overhang  and  partially  to  close  its  orifice. 
The  ante-chamber  to  the  nectary,  formed  by  the 
union  of  the  edges  of  the  labellum  to  the  column, 
which  is  large  in  0.  mascula  and  its  allies,  is  here 
small.  The  pouch-formed  rostellum  is  hollowed  out 
on  the  under  side  in  the  middle :  it  is  filled  with 
fluid.  The  viscid  disc  is  single  and  of  the  shape  of  a 
saddle  (figs.  C  and  E)  ;  it  carries  on  its  nearly  flat 
top  or  seat  the  two  caudicles  of  the  pollinia,  the  ends 
of  which  firmly  adhere  to  its  upper  surface.  Befor« 
the  membrane  of  the  rostellum  ruptures,  the  saddle- 
formed  disc  can  be  clearly  seen  to  ba  continuous  with 
the  rest  of  the  surface.  The  disc  i:^  partially  hidden 
and  kept  damp  (which  is  of  great  importance)  by  the 
over-folding  bases  of  the  two  anther-cells.  It  consists 
of  several  layers  of  minute  cells,  and  is  therefore  rather 
thick ;  it  is  lined  beneath  with  a  layer  of  highly  ad- 
hesive matter,  which  is  formed  within  the  rostellum. 
It  corresponds  strictly  to  the  two  minute,  oval,  sepa- 
rate discs  to  which  the  two  caudicles  of  0.  mascula 
and  its  allies  are  attached. 

When  the  flower  opens  and  the  rostellum  has 
become  symmetrically  ruptured,  either  from  a  touch 
or  spontaneously  (I  know  not  which),  the  slightest 
pressure  depresses  the  lip,  that  is,  the  lower  and  bi- 
lobed  portion  of  the  exterior  membrane  of  the  ros- 
tellum, which  projects  into  the  mouth  of  the  nectary. 


18 


OPHEE.E. 


Chap.  I. 


Fig.  3. 


Orchis  pyrajiidalis. 


Obap.  L  OECHIS   PYEAMIDALIS.  19 


Description  of  Ym.  8. 

«,     anther.  ^-      labellum. 

s,s.  stigma.  ^'.     guiding  plate  on  the  labellum. 

r.     rostellum.  n.     nectary. 

A.  Front   view,   with    all    the    sepals   and    petals   removed,   except   the 

labellum. 

B.  Side  view,  with  all  the  sepals  and  petals  removed,  with  the  labellum 

longitudinally  bisected,  and  with  the  near  side  of  the  upper  part 
of  the  nectary  cut  away. 

C.  The  two  pollinia  attached  to  the  saddle-shaped  viscid  disc. 

D.  The  disc  after  the  first  act  of  contraction,  with  no  object  seized. 

E.  The  disc  seen  from  above,  and  flattened  by  force,  with  one  polliniura 

removed;  showing  a  depression  in  its  surface,  by  which  the  second 
movement  of  the  pollinium  is  effected. 

F.  The  pollinia  removed  by  the  insertion  of  a  needle  into  the  nectary,  after 

the  saddle  has  clasped  the  needle  by  the  first  act  of  contraction. 
O.  The  same  pollinia  after  the  second  movement  and   their  consequent 
depression. 


20  OPHEE^.  Chap.  1. 

When  the  lip  is  depressed,  the  under  and  viscid  surface 
of  the  disc,  still  remaining  in  its  proper  place,  is  un- 
covered, and  is  almost  certain  to  adhere  to  the  touch- 
ing object.  Even  a  human  hair,  when  pushed  into 
the  nectary,  is  stiff  enough  to  depress  the  lip  or 
pouch ;  and  the  viscid  surface  of  the  saddle  adheres 
to  it.  If,  however,  the  lip  be  pushed  only  slightly, 
it  springs  back  and  recovers  the  under  side  of  the 
saddle. 

The  perfect  adaptation  of  the  parts  is  well  shown  by 
cutting  off  the  end  of  the  nectary  and  inserting  a 
bristle  at  that  end ;  consequently  in  a  reversed  direc- 
tion to  that  in  which  moths  insert  their  proboscides ; 
and  it  will  be  found  that  the  rostellum  may  easily  be 
torn  or  penetrated,  but  that  the  saddle  is  rarely  or 
never  caught.  When  the  saddle  together  with  the 
pollinia  is  removed  on  a  bristle,  the  under  lip  in- 
stantly curls  closely  inwards,  and  leaves  the  orifice  of 
the  nectary  more  open  than  it  was  before ;  but  whether 
this  is  of  much  service  to  the  moths  which  frequent 
the  flowers,  and  consequently  to  the  plant,  I  will  nol! 
pretend  to  decide. 

Lastly,  the  labellum  is  furnished  with  two  pro- 
minent ridges  (/',  figs.  A,  B),  sloping  down  to  the 
middle  and  expanding  outwards  like  the  mouth  of  a 
decoy ;  these  ridges  serve  to  guide  any  flexible 
body,  like  a  fine  bristle  or  hair,  into  the  minute  and 
rounded  orifice  of  the  nectary,  which,  small  as  it 
already  is,  is  partly  choked  up  by  the  rostellum. 
This  contrivance  of  the  guiding  ridges  may  be  com- 
pared to  the  little  instrument  sometimes  used  for 
guiding  a  thread  into  the  fine  eye  of  a  needle. 

Now  let  us  see  how  these  parts  act.  I^et  a  moth 
insert  its  proboscis  (and  we  shall  presently  see  how 
frequently   the   flowers   are   visited   by  Lepidoptera) 


Chap.  I.  ORCHIS  PYRAMIDALIS.  21 

between  the  guiding  ridges  of  the  labellum,  or  iusert 
a  fine  bristle,  and  it  is  conducted  safely  to  the  minute 
orifice  of  the  nectary,  and  can  hardly  fail  to  depress 
the  lip  of  the  rostellum  ;  this  being  effected,  the 
bristle  comes  into  contact  with  the  now  naked  and 
sticky  under  surface  of  the  suspended  saddle-formed 
disc.  When  the  bristle  is  removed,  the  saddle  with 
the  attached  pollinia  is  removed.  Almost  instantly, 
as  soon  as  the  saddle  is  exposed  to  the  air,  a  rapid 
movement  takes  place,  and  the  two  flaps  curl  inwards 
and  embrace  the  bristle.  When  the  pollinia  are 
pulled  out  by  their  caudicles,  by  a  pair  of  pincers, 
so  that  the  saddle  has  nothing  to  clasp,  I  observed 
that  the  flaps  curled  inwards  so  as  to  touch  each 
other  in  nine  seconds  (see  fig.  D),  and  in  nine  more 
seconds  the  saddle  was  converted  by  the  flaps  curl- 
ing still  more  inwards  into  an  apparently  solid  ball. 
The  proboscides  of  the  many  moths  which  I  have 
examined,  with  the  pollinia  of  this  Orchis  attached 
to  them,  were  so  thin  that  the  tips  of  the  flaps  just 
met  on  the  under  side.  Hence  a  naturalist,  who 
sent  me  a  moth  with  several  saddles  attached  to  its 
proboscis,  and  who  did  not  know  of  this  movement, 
very  naturally  came  to  the  extraordinary  conclusion 
that  the  moth  had  cleverly  bored  through  the  exact 
centres  of  the  so-called  sticky  glands  of  some 
Orchid. 

Of  course  this  rapid  clasping  movement  helps  to  fix 
the  saddle  upright  on  the  proboscis,  which  is  very 
important ;  but  the  viscid  matter  setting  hard  raj)idly 
would  probably  suffice  for  this  end,  and  the  real  object 
gainf^d  by  the  clasping  or  curling  movement  is  the 
divergence  of  the  pollinia.  The  pollinia,  being  at- 
tached to  the  flat  top  or  seat  of  the  saddle,  project  at 
first  straight  up  and  nearly  parallel  to  each   other  ; 


22  OPHllE.^.  Chap.  I. 

but  as  the  flat  top  curls  round  the  cylindrical  and 
thin  proboscis,  or  round  a  bristle,  the  pollinia  neces- 
sarily diverge.  As  soon  as  the  saddle  has  clasped  the 
bristle  and  the  pollinia  have  diverged,  a  second  move- 
ment commences,  which  action,  like  the  last,  is  ex- 
clusively due  to  the  contraction  of  the  saddle-shaped 
disc  of  membrane,  as  will  be  more  fully  described  in 
the  ninth  chapter.  This  second  movement  is  the 
same  as  that  in  0.  mascula  and  its  allies,  and  causes 
the  divergent  pollinia,  which  at  first  projected  at  right 
angles  to  the  needle  or  bristle  (see  fig.  F),  to  sweep 
through  an  angle  of  nearly  ninety  degrees  towards  the 
tip  of  the  needle  (see  fig.  G),  so  as  to  become  de- 
pressed and  finally  to  lie  in  the  same  plane  with  the 
needle.  In  three  specimens,  this  second  movement 
was  effected  in  from  thirty  to  thirty -four  seconds  after 
the  removal  of  the  pollinia  from  the  anther-cells,  and 
therefore  in  about  fifteen  seconds  after  the  saddle  had 
clasped  the  bristle. 

The  use  of  this  double  movement  becomes  evident 
if  a  bristle  with  pollinia  attached  to  it,  which  have 
diverged  and  become  depressed,  be  pushed  between 
the  guiding  ridges  of  the  labellum  into  the  nectary 
of  the  same  or  another  flower  (compare  figs.  A  and 
G)  ;  for  the  two  ends  of  the  pollen-masses  will  be 
found  now  to  have  acquired  such  a  position  that  the 
end  of  the  one  strikes  against  the  stigma  on  the  one 
side,  and  the  end  of  the  other  at  the  same  moment 
strikes  against  the  stigma  on  the  opposite  side.  The 
secretion  on  the  stigmas  is  so  viscid  that  when  the 
pollinia  are  withdrawn,  the  elastic  threads  by  which 
the  packets  of  pollen  are  bound  together  are  ruptured  ; 
and  some  dark-green  grains  may  be  seen,  even  by  the 
naked  eye,  remaining  on  the  two  white  stigmatic  sur- 
faces.    I  have  shown  this  little  experiment  to  several 


Chap.  I.  ORCHIS   PYEAMIDALIS.  23 

persons,  and  all  have  expressed  the  liveliest  admiration 
at  the  perfection  of  the  contrivance  by  which  this 
Orchid  is  fertilised. 

As  in  no  other  plant,  or  indeed  in  hardly  any 
animal,  can  adaptations  of  one  part  to  another,  and 
of  the  whole  to  other  organisms  widely  remote  in  the 
scale  of  nature,  be  named  more  perfect  than  those 
presented  by  this  Orchis,  it  may  be  w^orth  while 
briefly  to  sum  them  up.  As  the  flowers  are  visited 
both  by  day  and  night-flying  Lepidoptera,  it  is  not 
fanciful  to  believe  that  the  bright-purple  tint  (whether 
or  not  specially  developed  for  this  purpose)  attracts 
the  day-fliers,  and  the  strong  foxy  odour  the  night- 
fliers.  The  upper  sepal  and  two  upper  petals  form  a 
hood  protecting  the  anther  and  stigmatic  surfaces 
from  the  weather.  The  labellum  is  developed  into  a 
long  nectary  in  order  to  attract  Lepidoptera,  and  we 
shall  presently  give  reasons  for  suspecting  that  the 
nectar  is  purposely  so  lodged  that  it  can  be  sucked 
only  slowly  (very  differently  from  what  occurs  in  most 
other  plants),  in  order  to  give  time  for  the  viscid 
matter  on  the  under  side  of  the  saddle  to  set  hard 
and  dry.  He  who  will  insert  a  fine  and  flexible 
bristle  into  the  expanded  mouth  of  the  flower  between 
the  sloping  ridges  on  the  labellum,  will  not  doubt 
that  they  serve  as  guides  and  effectually  prevent  the 
bristle  or  proboscis  from  being  inserted  obliquely  into 
the  nectary.  This  latter  circumstance  is  of  manifest 
importance,  for,  if  the  proboscis  were  inserted  ob- 
liquely, the  saddle-formed  disc  would  become  attached 
obliquely,  and  after  the  compounded  movement  of  the 
pollinia  they  would  not  strike  the  two  lateral  stigmatic 
surfaces. 

Then  we  have  the  rostellum  partially  closing  the 
mouth  of  the  nectary,  like  a  trap  placed  in  a  run  for 


24  OPHREiE.  Chap.  L 

game ;  and  the  trap  so  complex  and  perfect,  with  its 
symmetrical  lines  of  rnptnre  forming  the  saddle- 
shaped  disc  above,  and  the  lip  of  the  pouch  below  ; 
and,  lastly,  this  lip  so  easily  depressed  that  the  pro- 
boscis of  a  moth  can  hardly  fail  to  uncover  the  viscid 
disc  and  adhere  to  it.  But  if  this  fails  to  occur,  the 
elastic  lip  rises  and  covers  again  the  viscid  surface, 
so  as  to  keep  it  damp.  The  viscid  matter  within  the 
rostellum  is  attached  to  the  saddle-shaped  disc  alone, 
and  is  surrounded  by  fluid,  so  that  it  does  not  set  hard 
till  the  disc  is  withdrawn.  The  upper  surface  of  the 
saddle,  with  the  attached  caudicles,  is  also  kept 
damp  by  the  bases  of  the  anther-cells,  until  it  is 
withdrawn,  and  then  the  curious  clasping  movement 
instantly  commences,  causing  the  pollinia  to  diverge, 
followed  by  the  movement  of  depression,  which  move- 
ments together  are  exactly  fitted  to  cause  the  ends 
of  the  two  pollen-masses  to  strike  the  two  stigmatic 
surfaces.  These  stigmatic  surfaces  are  not  so  sticky 
as  to  tear  off  the  whole  poUinium  from  the  proboscis 
of  the  moth,  but  by  rupturing  the  elastic  threads  to 
secure  a  few  packets  of  pollen,  leaving  plenty  for  other 
flowers.* 

But  let  it  be  observed  that,  although  the  moth  pro- 
bably takes  a  considerable  time  to  suck  the  nectar  of 
a  flower,  yet  the  movement  of  depression  in  the  pol- 
linia does  not  commence  (as  I  know  by  trial)  until 
they  are  fully  withdrawn  ;  nor  will  the  movement  be 
completed,  and  the  pollinia  properly  placed  for  strik- 
ing the  stigmatic  surfaces,  until  about  half  a  minute 
has  elapsed,  which  will  give  ample  time  for  the  moth  to 


*  The  late  Prof.  Treviranus  has  bnt  points  out  two  unimportant 
confirmed  ('  Botanische  Zeitung,'  inaccuracies  in  the  drawing  which 
1863,  p.  241)  all  my  observations,       I  have  given. 


Chap.  I  ORCHIS    USTULATA.  25 

fly  to  another  plant,  and  thus  effect  a  union  between 
two  distinct  individuals. 

Orchis  ustulata  *  resembles  0.  pyramidalis  in  some 
important  respects,  and  differs  from  it  in  others.  The 
labellum  is  deeply  channelled,  and  the  channel  which 
replaces  the  guiding  ridges  of  0.  pi/ramidalifi  leads  to 
the  small  triangular  orifice  of  the  short  nectary.  The 
upper  angle  of  the  triangle  is  overhung  by  the  ros- 
tellumj  the  pouch  of  which  is  rather  pointed  below. 
In  accordance  with  this  position  of  the  rostellum, 
close  to  the  mouth  of  the  nectary,  the  stigma  is 
double  and  lateral.  This  species  shows  in  an  interest- 
ing manner  how  easily  two  distinct  stigmas,  like  those 
of  0.  pyramidalis,  might  be  converted  into  a  single 
one,  by  becoming  at  first  slightly  lobed  like  that  of 
0.  masGula,  and  then  acquiring  its  present  structure. 
For  directly  beneath  the  rostellum  there  is  a  narrow 
transverse  rim,  formed  of  true  stigmatic  tissue,  which 
connects  together  the  two  lateral  stigmas  ;  so  that 
if  this  rim  were  widened,  the  tv>'o  stigmas  would  be 
converted  into  a  single  transverse  one.  Conversely 
a  single  stigma  might  thus  easily  be  converted  into  a 
double  one.  The  pollinia  undergo  the  usual  move- 
ment of  depression,  and  in  acquiring  this  position 
the  two  diverge  slightly,  so  as  to  be  ready  to  strike  the 
two  lateral  stigmas. 

Orchis  (sub-genus  Ilimantoglossum)  hircina. — A  fine 
specimen  of  this  extremely  rare  British  plant,  the 
Lizard  Orchis,  with  its  curious  elongated  labellum, 
was  sent  me  by  Mr.  Oxenden.  The  two  pollinia 
arise  from   a  single  almost   square  disc ;    and   when 


*  I  am  greatly  indebted  to  IMr.  kindness  in  supplying  me  with 
G.  Chichester  Oxenden  of  Broome  living  plants,  and  information  re- 
Park  fur  frtsh  specimens  of  this  gaiding  many  of  the  rarer  Britisn 
Orchis,  and  for  his   never-tiring  Orchids. 


26  CPHRE^.  Chap.  L 

they  are  removed  from  their  cells,  they  do  not  di- 
verge, but  become  depressed,  sweeping  through  an 
angle  of  ninety  degrees,  in  about  thirty  seconds.  They 
are  then  in  a  proper  position  for  striking  the  single 
large  stigma  which  lies  beneath  the  rostellum.  In  the 
case  of  0.  pjramidalis  we  have  seen  that  the  depression 
of  the  two  poUinia  is  effected  by  the  contraction  of 
the  disc  in  front  of  each,  two  furrows  or  valleys  being 
there  formed ;  whilst  with  the  present  species,  the 
whole  front  of  the  disc  contracts  or  sinks  down,  the 
iront  part  being  thus  separated  from  the  hinder  part 
by  an  abrupt  step. 

Acer  as*  {Orchis)  antliropoiohora. — The  caudicles  of 
the  pollinia  are  unusually  short ;  the  nectary  consists 
of  two  minute  rounded  depressions  in  the  labellum; 
the  stigma  is  transversely  elongated;  and  lastly  the 
two  viscid  discs  lie  so  close  together  within  the  ros- 
tellum that  they  affect  each  other's  outline.  This 
latter  fact  is  worth  notice,  as  a  step  towards  the  two 
becoming  absolutely  confluent,  as  in  the  following 
species  of  Aceras,  in  0.  'pyramidalis  and  hircina. 
Nevertheless,  in  Aceras  a  single  pollinium  is  some- 
times removed  by  insects,  though  more  rarely  than 
with  the  other  species  of  Orchis. 

Aceras  {Orchis)  longibracteata, — Mr.  Moggridge  has 
given  an  interesting  account,  together  with  a  figure, 
of  this  plant  which  grows  in  the  South  of  France.f 
The  pollinia  are  attached  to  a  single  viscid  disc. 
When  they  are  removed  they  do  not  diverge  as  in 
0,  pyramidalis,  but  converge   and  then   undergo  the 


*  The  separation  of  this  genus  occurrence  of  numerous  hybrids, 

is  evidently  artificial.    It  is  a  true  naturally  produced,  between  this 

Orchis,   but    witli    a    very   short  At-eras  and  Orchis  galeata. 

nectary.      Dr.   Weddell   has   de-  t    '  Journ.     Linn.     See.     Bot.* 

scribed  (' Annales  des  Sc.  Nat.,*  vol.  viii.  1865,  p.  256.     He  gives 

3  ser.   Bot.  torn,  xviii.  p.  6)  the  also  a  figure  of  Orchis  hircina. 


CHAr.  I.  NIGRITELLA   ANGUSTIFOLIA.  27 

movement  of  depression.  The  most  remarkable  point 
about  this  species  is  that  insects  seem  to  suck  nectar 
out  of  minute  open  cells  in  the  honeycombed  surface 
of  the  labellum.  The  flowers  are  visited  by  various 
hymenopterous  and  dipterous  insects ;  and  the  author 
saw  the  pollinia  attached  to  the  forehead  of  a  large 
bee,  the  Xylocopa  viola  cea. 

Neotinea  {Orchis)  intada. — Mr.  Moggridge  sent  me 
from  North  Italy  living  specimens  of  this  very  rare 
British  plant,  which,  as  he  informed  me,  is  remark- 
able from  producing  seeds  without  the  aid  of  insects. 
When  insects  were  carefully  excluded  by  me,  almost 
all  the  flowers  produced  capsules.  Their  fertilisation 
follows  from  the  pollen  being  extremely  incoherent,  so 
as  to  fall  spontaneously  on  the  stigma.  Nevertheless 
a  short  nectary  is  present,  the  pollinia  possess  small 
viscid  discs,  and  all  the  parts  are  so  arranged  that, 
if  insects  were  to  visit  the  flowers,  the  pollen-masses 
would  almost  certainly  be  removed  and  carried  to 
another  flower,  but  not  so  effectually  as  with  most 
other  orchids. 

Serapias  cordigera,  an  inhabitant  of  the  South  of 
France,  has  been  described  by  Mr.  Moggridge  in  the 
paper  just  referred  to.  The  pollinia  are  attached  to 
a  single  viscid  disc ;  when  first  withdrawn,  they  are 
bent  backwards,  but  soon  afterwards  move  forwards 
and  downwards  in  the  usual  manner.  As  the  stigmatic 
cavity  is  narrow,  the  pollinia  are  guided  into  it  by  two 
guiding  plates. 

Nigritella  angustifolia. — This  Alpine  species  is  said 
by  Dr.  H.  Miiller  *  to  differ  from  all  ordinary  orchids 
in  the  ovarium  not  being  twisted ;  so  that  the  labellum 
stands  on  the  upper  side  of  the  flower,  and  insects 


Nature,'  Dec.  31,  1874,  p.  169. 


28  OPHRE^.  Chap.  I. 

alight  on  the  opposite  sepals  and  petals.  As  a  con- 
sequence of  this,  when  a  butterfly  inserts  its  proboscis 
into  the  narrow  entrance  of  the  nectary,  the  yiscid  discs 
become  attached  to  the  lower  surface  of  the  proboscis, 
and  the  pollinia  afterwards  move  upwards,  instead  of 
as  in  all  other  orchids  downwards.  They  are  then  in 
the  proper  position  for  striking  the  stigma  of  the  next 
flower  which  is  visited.  Dr.  Miiller  remarks  that  the 
flowers  are  frequented  by  an  extraordinary  number  of 
butterflies. 

I  have  now  described  the  structure  of  most  of  the 
British  and  of  a  few  foreign  species  in  the  genus 
Orchis  and  its  close  allies.  All  these  species,  with  the 
exception  of  the  Neotinea,  require  the  aid  of  insects  for 
their  fertilisation.  This  is  obvious  from  the  fact  that 
the  pollinia  are  so  closely  embedded  in  the  anther-cells, 
and  the  ball  of  viscid  matter  in  the  pouch-formed 
rostellum,  that  they  cannot  be  shaken  out  by  violence. 
We  have  also  seen  that  the  pollinia  do  not  assume  the 
proper  position  for  striking  the  stigmatio  surface  until 
some  time  has  elapsed;  and  this  indicates  that  they 
are  adapted  to  fertilise,  not  their  own  flow^ers,  but  those 
on  a  distinct  plant.  To  prove  that  insects  are  neces- 
sary for  the  fertilisation  of  the  flowers,  I  covered  up 
a  plant  of  Orchis  morio  under  a  bell-glass,  before 
any  of  its  pollinia  had  been  removed,  leaving  three 
adjoining  plants  uncovered ;  1  looked  at  the  latter 
every  morning,  and  daily  found  some  of  the  pollinia 
removed,  till  all  were  gone  with  the  exception  of  those 
in  a  single  flower  low  down  on  one  spike,  and  of  those 
in  one  or  two  flowers  on  the  summits  of  all  the  spikes, 
which  were  never  removed.  But  it  should  be  observed 
that  when  only  a  very  few  flowers  remain  open  on  the 
summits  of  the  spikes,  these  are  no  longer  conspicuous. 


Chap.  I.  FERTILISED   BY   INSECTS.  29 

and  would  consequently  be  rarely  visited  by  insects. 
I  then  looked  at  the  perfectly  healthy  plant  under 
the  bell-glass,  and  it  had,  of  course,  all  its  pollinia  in 
the  anther-cells.  I  tried  an  analogous  experiment  with 
specimens  of  0.  mascula  with  the  same  result.  It  de- 
serves notice  that  the  spikes  which  had  been  covered 
up,  when  subsequently  left  uncovered,  never  had  their 
pollinia  carried  away  by  insects,  and  did  not,  of  course, 
set  any  seed,  whereas  the  adjoining  plants  produced 
plenty  of  seed.  From  this  fact  it  may  be  inferred 
that  there  is  a  proper  season  for  each  kind  of  Orchis, 
and  that  insects  cease  their  visits  after  the  proper 
season  has  passed. 

With  many  of  the  hitherto  mentioned  species,  and 
with  several  other  European  kinds,  the  sterility  of  the 
flowers,  when  protected  from  the  access  of  insects, 
depends  solely  on  the  pollen-masses  not  coming  into 
contact  with  the  stigma.  This  has  been  proved  to  be 
the  case  by  Dr.  Hermann  Miiller,  who,  as  he  informs 
me,  applied  the  pollen-masses  of  Orchis  pjramidalis 
(44),  fasca  (6),  militaris  (14),  variegata  (3),  coriopJiora 
(6),  morio  (4),  maculata  (18),  mascula  (6),  latifolia  (8), 
incarnata  (3),  Oplirys  muscifera  (8),  Gymnadenia  conop- 
sea  (14),  alhida  (8),  Serminium  monorcliis  (6),  Epipogon 
aphijllus  (2),  Epipactis  laiifoUa  (14:),palustris  (4),  Listera 
ovata  (5),  and  Cypripedmm  calceolus  (2),  to  their  own 
stigmas,  and  full-sized  capsules,  containing  seeds  in 
appearance  good,  were  formed.  The  numbers  placed 
after  the  names  of  the  species  show  how  many  flowers 
were  tried  in  each  case.  These  facts  are  remarkable, 
because  Mr.  Scott   and   Fritz  Miiller*   have  proved 


♦  An  abstract  of  their  observa-       ticaiion,'  chap.  xvii.  2ud  edit,  vol 
tions  is  given  in  my  'Variation  of      ii.  p.  114. 
Animals  and  Plants  under  Domes- 


30  OPHREJE.  CiiAP.  1. 

that  various  exotic  species,  both  in  this  country  and 
in  their  native  homes,  invariably  fail  to  yield  seed- 
capsules,  when  the  flowers  are  fertilised  with  their  own 
pollen. 

From  the  observations  already  given,  and  from 
what  will  hereafter  be  shown  with  respect  to  Gym 
nadenia,  Habenaria,  and  some  other  species,  it  is  a 
safe  generalisation*  that  species  with  a  short  and 
not  very  narrow  nectary  are  fertilised  by  beesf  and 
flies;  whilst  those  with  a  much  elongated  nectary, 
or  one  having  a  very  narrow  entrance,  are  fertilised 
by  butterflies  or  moths,  these  being  provided  with 
long  and  thin  proboscides.  We  thus  see  that  the 
structure  of  the  flowers  of  Orchids  and  that  of 
the  insects  which  habitually  visit  them,  are  corre- 
lated in  an  interesting  manner, — a  fact  which  has 
been  amply  proved  by  Dr.  H.  Miiller  to  hold  good 
with  many  of  the  Orchidese  and  other  kinds  of 
plants. 

With  respect  to  Orchis  pyramidalis,  which  possesses, 
as  we  have  seen,  an  elongated  nectary,  Mr.  Bond  was 
so  kind  as  to  send  me  a  large  number  of  Lepidoptera, 
out  of  which  I  selected  twenty-three  species,  enumer- 
ated in  the  following  list,  with  the  poUinia  of  this 
Orchid,  which  can  easily  be  recognised,  attached  to 
their  proboscides. 

*  Some  remarks  to  this  effect  near  the  Jardin  de  la  Faculte  (at 

were    given    in    my    "Notes   on  Toulouse?)  complained   tliat   his 

the  Fertilisation  of  Orchids,"   in  bees   retivned   from    the    garden 

'  Annals  and  Mag.  of  Nat.  Hist.'  with    their   hetcls  charged   witL 

Sept.  1869,  p.  2.  yellow  bodies,  of  which  tiiey  could 

t  M.  Me'niere  (in  'Bull.  Bot.  not  free  themselves.    This  is  good 

Soc.  de  Friiuce,'  torn.  i.  1854,  p.  evidence  how  firmly  the  poliiuia 

370)  says  he  saw  in  Dr.  Gue'pin's  are  attached.     There  is,  however, 

collection,  bees  collected  at  San-  nothing  to  show  whether  the  pol- 

mur  with  the  poUinia  of  Orchids  linia   in  these  cases  belonged  to 

attached  to  their  heads ;  and  he  the  genus  Orchis  or  to  some  other 

states  that  a  person  who  kept  bees  genus  of  the  family. 


Cjiai'.  1. 


FERTILISED    BY    INSECTS. 


31 


Polyommatus  alexia. 
Lycsena  phlseas. 
Arge  galathea. 
Hesperia  sylvanus. 

„        linea. 
Syrichthus  alveolus. 
Anthrocera  filipendulse. 

„  trifolii.* 

Lithosia  complana. 
Leucania  lithargyria  (two  speci- 
mens). 
Caradiina  blanda. 
„         al  sines, 
Agrotis  cataleuca. 


Eubolia  mensuraria   (two   speci- 
mens). 

Hadena  dentina. 

Heliothis   marginata  (two   speci- 
mens). 

Xylophasia  sublustris  (two  speci- 
mens). 

Euclidia  glyphica. 

Toxoeampa  pastinum. 

Melauippe  rivaria. 

Spilodes  palealis. 
„        cinctalis. 

Acontia  luctuosa. 


A  large  majority  of  these  moths  and  butterflies 
had  two  or  three  pairs  of  pollinia  attached  to  them, 
and  invariably  to  the  proboscis.  The  Acontia  had 
seven  pair   (fig.  4),  and  the  Fig.  4. 

Caradrina  no  less  than  eleven 
pair !  The  proboscis  of  this 
latter  moth  presented  an  ex- 
traordinary arborescent  ap- 
pearance. The  saddle-formed 
discs,  each  bearing  a  pair  of 
pollinia,  adhered  to  the  pro- 
boscis, one  before  the  other, 

witn  perfect  symmetry  ;  and    Head  and  proboscis  of  Acontia  luc- 
.,  .      p  n  o  ,T  .,  tuosn  with  seven  pair  of  oollinia 

this   lolloWS   Irom   the    moth         of    Orchis  pyramidalis  attached 

having  always  inserted  its  ^°  ^^^  proboscis. 
proboscis  into  the  nectary  in  exactly  the  same  manner, 
owing  to  the  presence  of  the  guiding  plates  on  the 
labellum.  The  unfortunate  Caradrina,  with  its  pro- 
boscis thus  encumbered,  could  hardly  have  reached 
the  extremity  of  the  nectary,  and  would  soon  have 


♦  I  am  imlebted  to  Mr.  Parfitt 
for  an  examination  of  tliis  moth, 
wliich  is  mentioned  in  the  '  En- 
toniologifct's  Weekly  Intelligencer,' 
vol.  ii.  p.  182,  and  vol.  iii.  p.  3, 
Oct.  3,  1857.     The  pollinia  were 


erroneously  thought  to  belong  to 
Ophrys  apifera.  The  pollen  had 
changed  from  its  natural  green 
colour  to  yellow :  on  wasliing  it, 
however,  and  drying  it,  the  green 
tint  returned. 


32  OFHEE^.  Chap.  I. 

been  starved  to  death.  Both  these  moths  must  have 
sucked  many  more  than  the  seven  and  eleven  flowers, 
of  which  they  bore  the  trophies,  for  the  earlier  at- 
tached pollinia  had  lost  much  of  their  pollen,  showing 
that  they  had  touched  many  viscid  stigmas. 

The  above  list  proves  that  many  different  species 
of  Lepidoptera  visit  the  same  kind  of  Orchis.  The 
Hadena  dentina  also  frequents  Habenaria.  Probably 
all  the  Orchids  provided  with  elongated  nectaries 
are  visited  indifferently  by  many  kinds  of  moths. 
Whether  any  of  the  British  Orchids  are  fertilised 
exclusively  by  special  insects  confined  to  certain 
localities  is  very  doubtful ;  but  we  shall  hereafter  see 
that  Epipadis  latifoUa  seems  to  be  fertilised  by  wasps 
alone.  I  have  twice  observed  plants  of  Gymnadenia 
conopea,  which  had  been  transplanted  into  a  garden 
many  miles  from  its  native  home,  with  nearly  all 
their  pollinia  removed.  Mr.  Marshall  of  Ely*  has 
made  the  same  observation  on  similarly  transplanted 
specimens  of  0.  macuJata.  On  the  other  hand  fifteen 
plants  of  Ophrtjs  muscifera  had  not  one  pollen-mass 
there  removed.  Malaxis  paludosa  was  placed  in  a 
bog  about  two  miles  from  that  in  which  it  naturally 
grew  ;    and  it  had  most  of  its  pollinia  immediately 

removed. 

The  list  which  follows  serves  to  show  that  insects  m 
most  cases  perform  the  work  of  fertilisation  effectually. 
But  the  list  by  no  means  gives  a  fair  idea  how  effectu- 
ally it  is  done  ;  for  I  have  often  found  nearly  all  the 
pollinia  removed,  but  kept  an  exact  record  only  in 
exceptional  cases,  as  may  be  seen  by  the  appended 
remarks.     Moreover,  in  most  cases,  the  pollmia  which 

»  '  Gardener's  Chronicle,'  1861,  marks  of  mine  on  this  subject 
n  73.  Mr.  Marshall's  communi-  previouslpublished  m  the  Gar- 
cat  on  was  in  answer  to  some  re-      dener's  Chronicle,  lb60,  p.  528. 


Chav.  I. 


FERTILISED    BY    INSECTS. 


33 


had  not  been  removed  were  in  the  upper  flowers 
beneath  the  buds,  and  many  of  these  would  probably 
have  been  subsequently  carried  away.  I  have  often 
found  an  abundance  of  pollen  on  the  stigmas  of  flowers 
which  had  not  their  own  pollinia  removed,  showing 
that  they  had  been  visited  by  insects.  In  many  other 
cases  the  pollinia  had  been  removed,  but  no  pollen  had 
been  as  vet  left  on  the  stigmas. 


Orchis  morio.     Three  small  plants.    N.| 
Kent / 

Orchis  morio.  Thirty-eight  plants.  N.^ 
Kent.  These  plants  were  examined 
after  nearly  four  weeks  of  extraordi- 
narily cold  and  wet  weather  in  1860 ; 
and  therefore  under  the  most  unfavour- 
able circumstances 

Orchis    pyramidalis.      Two    plants.      N.| 
Kent  and  Devonshire.         .  .          ./ 

Orchis  pyramidalis.  Six  plants  from  two"! 
protected  valleys.     Devonshire     .          .  / 

Orchis  pyramidalis.  Six  plants  from  al 
much  exposed  bank.    Devonshire  .  j 

Orchis  maculata.     One  plant.     Stafford-i 
shire.     Of  the  twelve  flowers  which  had] 
not  their  pollinia  removed,  the  greater!- 
number  were  young  flowers  under  the 
buds  .....         .J 

Orchis  maculata.     One  plant.     Surrey     . 

Orcliis  maculata.  Two  plants.  N.  and) 
S.Kent / 

Orchis  latifolia.  Nine  plants  from  S. 
Kent,  sent  me  by  the  Rev.  B.  S.  Maiden. 
Tl-.e  flowers  were  all  mature 

Orchis  fusca.  Two  plants.  S.  Kent.l 
Flowers  quite  mafure,  and  even  withered/ 

Aceras  anlhropoi)hora.  Four  plants.  S.' 
Kent  ..... 


':} 


£5 


22 
110 

39 

102 
57 

32 

21 

28 

50 

8 
63 


5  o 


s  .:;  tn  .=  i 


2  c  ®  2  o 

3  a  3  05  o 


23 


5 

17 

27 

5 
6 


193 


G6 

166 

12 

7 
50 

119 

54 
34 


34  OFHEE^.  Chap.  I. 

In  the  second  lot  of  0.  morio,  in  the  preceding  list, 
we  see  the  injurious  effects  of  the  extraordinary  cold 
and  wet  season  of  1860  on  the  visits  of  insects,  and, 
consequently,  on  the  fertilisation  of  this  Orchid,  very 
few  seed-capsules  having  been  produced. 

I  have  examined  spikes  of  0.  pi/ramidalis  in  which 
every  single  expanded  flower  had  its  poUinia  removed. 
The  forty-nine  lower  flowers  of  a  spike  from  Folkestone 
(sent  me  by  Sir  Charles  Lyell)  actually  produced  forty- 
eight  fine  seed-capsules ;  and  of  the  sixty-nine  lower 
flowers  in  three  other  spikes,  seven  alone  had  failed  to 
produce  capsules.  These  facts  show  how  well  moths 
and  butterflies  perform  their  office  of  marriage-priests.* 

The  third  lot  of  0.  pjrainidalis  in  the  above  list 
grew  on  a  steep  grassy  bank,  overhanging  the  sea  near 
Torquay,  and  where  there  were  no  bushes  or  other 
shelter  for  Lepidoptera ;  being  surprised  how  few  pol- 
linia  had  been  removed,  though  the  spikes  were  old 
and  very  many  of  the  lower  flowers  withered,  I  gathered, 
for  comparison,  six  other  spikes  from  two  bushy  and 
sheltered  valleys,  half  a  mile  on  each  side  of  the 
exposed  bank  ;  these  spikes  were  certainly  younger, 
and  would  probably  have  had  several  more  of  their 
pollinia  removed ;  but  in  their  present  condition  we 
see  how  much  more  frequently  they  had  been  visited  by 
moths,  and  consequently  fertilised,  than  those  growing 
on  the  much  exposed  bank.  The  Bee  Ophrys  and 
0.  pjramidalis  grow  mingled  together  in  many  parts 
of  England  ;  and  they  did  so  here,  but  the  Bee  Oj)hrys, 
instead  of  being,  as  usual,  the  rarer  species,  was  here 


♦  In  the  summer  of  1875,  whicli  ing  fertilised ;  and  on  tliis  occasion 
was  a  very  wet  one,  I  gatliered  six  only  119  flowers  produced  cap- 
unusually  fine  spikes  of  0.  pyra-  sules,  183  Laving  faiUd  to  do  so. 
midulis.  Tliese  bore  302  flowers.  Six  sjakes  of  O.  maculata  bore  187 
excluding  fourteenwliich  were  still  flowers,  of  which  eighty-two  pro- 
fuliy  expanded  and  capable  of  be-  duced  capsules,  105  having  failed. 


Chap.  I.  FERTILISED   BY   INSECTS.  35 

raucli  more  abundant  than  0.  pyramidalis.  !No  one 
would  readily  have  suspected  that  one  chief  reason  of 
this  difference  probably  was,  that  the  exposed  situation 
was  unfayourable  to  Lepidoptera,  and  therefore  to  the 
seeding  of  0.  'pijramiclalis ;  whereas,  as  we  shall  here- 
after see,  the  Bee  Ophrys  is  independent  of  insects. 

Many  spikes  of  0.  latifoUa  were  examined,  because, 
being  familiar  with  the  usual  state  of  the  closely-allied 
0.  maculata,  I  was  surprised  to  find  in  nine  nearly 
withered  spikes  (as  may  be  seen  in  the  list)  how  few 
pollinia  had  been  removed.  In  one  instance,  however, 
0.  maculata  had  been  even  worse  fertilised ;  for  seven 
spikes  with  315  flowers,  produced  only  forty-nine  seed- 
capsules — that  is,  on  an  average  only  seven  capsules 
on  each  spike.  In  this  case  the  plants  formed  larger 
beds  than  I  had  ever  before  seen  ;  and  I  imagine  that 
there  were  too  many  flowers  for  the  insects  to  visit 
and  fertilise  all  of  them.  On  some  other  plants  of 
0.  maculata  growing  at  no  great  distance,  above  thirty 
capsules  had  been  produced  by  each  spike. 

Orchis  fusca  offers  a  still  more  curious  case  of 
imperfect  fertilisation.  I  examined  ten  fine  spikes 
from  two  localities  in  South  Kent,  sent  to  me  by  Mr. 
Oxenden  and  Mr.  Maiden  :  most  of  the  flowers  on  these 
spikes  were  partly  withered,  with  the  pollen  mouldy 
even  in  the  uppermost  flowers ;  we  may  therefore  infer 
that  no  more  pollinia  would  have  been  removed.  I 
examined  all  the  flowers  only  in  two  spikes,  on  account 
of  the  trouble  from  their  withered  condition,  and  the 
result  may  be  seen  in  the  list,  namely,  fifty-four 
flowers  with  both  pollinia  in  place,  and  only  eight 
with  one  or  both  removed.  In  this  Orchid,  and  in  0. 
latifoUa,  neither  of  which  had  been  sufficiently  visited 
by  insects,  there  were  more  flowers  with  one  pollinium 
than  with  both  removed.     I  casually  examined  many 


36  OPHKE^.  Chap.  I. 

flowers  in  the  other  spites  of  0.  fusca,  and  the  propor- 
tion of  pollinia  removed  was  evidently  not  greater 
than  in  the  two  in  the  list.  The  ten  spikes  bore 
altogether  358  flowers,  and,  in  accordance  with  the 
few  pollinia  removed,  only  eleven  capsules  had  been 
formed :  five  of  the  ten  spikes  produced  not  a  single 
capsule ;  two  spikes  had  only  one,  and  one  had  as 
many  as  four  capsules.  As  corroborating  what  I  have 
before  said  with  respect  to  pollen  being  often  found  on 
the  stigmas  of  flowers  which  retain  their  own  pollinia, 
I  may  add  that,  »of  the  eleven  flowers  which  had 
produced  capsules,  five  had  both  pollinia  still  within 
their  now  withered  anther-cells. 

From  these  facts  the  suspicion  naturally  arises  that 
0.  fusca  is  so  rare  a  species  in  Britain  from  not  being 
sufliciently  attractive  to  insects,  and  to  its  not 
producing  a  sufficiency  of  seed.  C.  K.  Sprengel* 
noticed,  that  in  Germany  0.  militaris  (ranked  by 
Bentham  as  the  same  species  with  0.  fusea)  is  likewise 
imperfectly  fertilised,  but  more  perfectly  than  our  0. 
fusca  ;  for  he  found  five  old  spikes  bearing  138  flowers 
which  had  set  thirty-one  capsules ;  and  he  contrasts  the 
state  of  these  flowers  with  those  of  Gymnadenia  conop- 
sea,  in  which  almost  every  flower  produces  a  capsule. 

An  allied  and  curious  subject  remains  to  be  discussed. 
The  existence  of  a  well-developed  spur-like  nectary 
seems  to  imply  the  secretion  of  nectar.  But  Sprengel, 
a  most  careful  observer,  thoroughly  searched  many 
flowers  of  0.  latifolia  and  morio,  and  could  never  find 
a  drop  of  neclar;   nor   could   Kriinitzt   find   nectar 


*  'Das  entdeckte  Geheimniss/  tung  der  Nektarien,'  1S33,  s.  28. 

etc.  s.  404.  See  also  '  Das  entdeckte  Geheim- 

t  Quoted  by  J.  G.  Kurr  in  his  niss,'  s.  403. 
^Untersuehungen  iibor  'lie  Bedeu- 


Chap.  I.  SECRETION   OF   NECTAR.  37 

either  in  the  nectary  or  on  the  hibellum  of  0.  morio, 
fusca,  7nilitaris,  maculata  or  latifolia.     I  have  looked 
to  all  our  common  British  species  and  could  find  no 
trace   of  nectar;    I    examined,   for   instance,    eleven 
flowers   of   0.   maculata^  taken  from  different   plants 
growing  in  different  districts,  and  taken  from  the  most 
favourable  position  on  each  spike,  and  could  not  find 
under   the   microscope   the   smallest  bead  of  nectar. 
Sprengel   calls   these   flowers   "  Scheinsaftblumen"    or 
sham-nectar-producers ; — he  believes  that  these  plants 
exist  by  an  organized  system  of  deception,  for  he  well 
knew  that  the  visits  of  insects  were  indispensable  for 
their  fertilisation.   But  when  we  reflect  on  the  incalcul- 
able number  of  plants  which  have  lived  during  a  great 
length  of  time,  all  requiring  that  insects  should  carry 
the  pollen-masses  from  flower  to  flower  in  each  gene- 
ration ;  and  as  we  further  know  from  the  number  of  the 
pollen-masses  attached  to  their  proboscides,  that  the 
same  insects  visit  a  large  number  of  flowers,  we  can 
hardly    believe   in   so    gigantic    an    imposture.      He 
who  believes   in   Sprengel's  doctrine  must   rank   the 
sense   or   instinctive   knowledge    of    many   kinds    of 
insects,  even   bees,  very  low  in   the   scale.     To  test 
the   intellect   of  moths   and   butterflies    I   tried    the 
following  little  experiment,  which  ought  to  have  been 
tried  on  a  larger  scale.     I   removed   a   few  already- 
opened   flowers   on   a   spike   of    0.  pjramiclalis,   and 
then  cut  off  about  half  the  length  of  the  nectaries 
of  the  six  next  non-expanded  flowers.     When  all  the 
flowers  were  nearly  withered,  I  found   that  thirteen 
of   the   fifteen   upper   flowers   with   perfect   nectaries 
had  their  pollinia  removed,  and  two  alone  had  their 
pollinia  still  in  the  anther-cells ;    of  the  six  flowers 
with  their  nectaries  cut  off,  three  had  their  pollinia 
removed,  and  three  were  still  in  place ;   and  this  in- 


38  OPHRE^.  Chap.  I. 

dicates  that  moths  do  not  go  to  work  in  a  quite  sense- 
less manner.* 

Nature  may  be  said  to  have  tried  this  same  experi- 
ment, but  not  quite  fairly;  for  Orchis  pyramidalis, 
as  shown  by  Mr.  Bentham,t  often  produces  monstrous 
flowers  without  a  nectary,  or  with  a  short  and  imperfect 
one.  Sir  C.  Lyell  sent  me  several  spikes  from  Folke- 
stone with  many  flowers  in  this  condition :  I  found  six 
without  a  vestige  of  a  nectary,  and  their  pollinia  had 
not  been  removed.  In  about  a  dozen  other  flowers, 
having  either  short  nectaries,  or  with  the  labellum 
imperfect,  the  guiding  ridges  being  either  absent  or 
developed  in  excess  and  rendered  foliaceous,  the 
pollinia  in  one  alone  had  been  removed,  and  the  ova- 
rium of  another  flower  was  swelling.  Yet  I  found 
that  the  saddle-formed  discs  in  these  eighteen  flowers 
were  perfect,  and  that  they  readily  clasped  a  needle 
when  inserted  in  the  proper  place.  Moths  had  removed 
the  pollinia,  and  had  thoroughly  fertilised  the  perfect 
flowers  on  the  same  spikes ;  so  that  they  must  have 
neglected  the  monstrous  flowers,  or,  if  visiting  them, 
the  derangement  in  the  complex  mechanism  of  the 
parts  had  hindered  the  removement  of  the  pollinia, 
and  prevented  their  fertilisation. 

Notwithstanding  these  several  facts  I  still  suspected 
that  nectar  must  be  secreted  by  our  common  Orchids, 


*  Kurr  ('  Beilcutung  der  Nek-  the  corolla,  leaving  the  nectary,  of 

tarien,'  1833,  p    123)  cut  off  the  forty  flowers  of  Orchis  morio,  and 

nectaries     of   fifteen    flowers    of  tliese  set   no  capsules;   and  this 

Gymnarhnia  comqjsea,  and  tliey  case  shows  that  insects  are  guided 

did  not  produce  a  single  capsule  :  to    the    flowers    by   the    corolla, 

he  also  tnated  in  the  same  man-  Sixteen   flowers    of   Platanthera 

ner  fifteen  flowers  of  Platanthera  treated  in  tlie  same  manner  bore 

or  Hahenaria  hifoUa,   and   these  only  one  capsule.    Similar  experi- 

set  only  five  capsules;  but  then  it  ments  made  by  him  on  Gymna- 

should  be  observed  that  the  nee-  denia  seem  to  me  open  to  doubt, 
taries  of  both  these  orchids  con-  t  'Handbook    of    the    British 

tain  free  nectar.     He  also  cut  off  Flora,'  1858,  p.  501. 


Chap.  I.  SECRETION    OF    NECTAR.  39 

and  I  determined  to  examine  0.  morio  rigorously.  As 
soon  as  many  flowers  were  open,  I  began  to  examine 
them  for  twenty-three  consecutive  days :  I  looked  at 
them  after  hot  sunshine,  after  rain,  and  at  all  hours  : 
I  kept  the  spikes  in  water,  and  examined  them  at 
midnight,  and  early  the  next  morning:  I  irritated 
the  nectaries  with  a  bristle,  and  exposed  them  to 
irritating  vapours :  I  took  flow^ers  which  had  lately  had 
their  pollinia  removed  by  insects,  of  which  fact  I  had 
independent  proof  on  one  occasion  by  finding  grains 
of  some  foreign  pollen  within  the  nectary  ;  and  1  took 
other  flowers,  which  judging  from  their  position  on  the 
spike,  would  soon  have  had  their  pollinia  removed  ; 
but  the  nectary  was  invariably  quite  dry.  After  the 
publication  of  the  first  edition  of  this  work,  I  one 
day  saw  various  kinds  of  bees  visiting  repeatedly  the 
flowers  of  this  same  Orchid,  so  that  this  w^as  evidently 
the  proper  time  to  examine  their  nectaries  ;  but  I  failed 
to  detect  under  the  microscope  even  the  minutest  drop 
of  nectar.  So  it  was  with  the  nectaries  of  0.  maculata 
at  a  time  when  I  repeatedly  saw  flies  of  the  genus 
Empis  keeping  their  proboscides  inserted  into  them 
for  a  considerable  length  of  time.  Orchis  pjramidalis 
was  examined  with  equal  care  with  the  same  result, 
for  the  glittering  points  within  the  nectary  were  abso- 
lutely dry.  AVe  may  therefore  safely  conclude  that 
the  nectaries  of  the  above-named  Orchids  neither  in 
this  country  nor  in  Germany  ever  contain  nectar. 

Whilst  examining  the  nectaries  of  0.  morio  and 
maculata^  and  especially  of  0.  pyramidalis  and  hircina^ 
I  was  surprised  at  the  degree  to  which  the  inner  and 
outer  membranes  forming  the  tube  or  spur  were  sepa- 
rated from  each  other, — also  at  the  delicate  nature  of 
the  inner  membrane,  which  could  be  penetrated  very 
easily, — and,  lastly,  at  the  quantity  of  fluid  contained 


40  OrnEE^.  Chap.  L 

between  the  two  membranes.  So  copious  is  this  fluid, 
that,  after  cutting  off  the  extremities  of  the  nectaries 
of  0.  2'>ijycimidalis^  and  gently  squeezing  them  on  glass 
under  the  microscope,  such  large  drops  of  fluid  exuded 
from  the  cut  ends,  that  I  concluded  that  at  last  I  had 
found  nectaries  which  contained  nectar;  but  when  I  care- 
fully made,  without  any  pressure,  a  slit  along  the  upper 
surface  of  other  nectaries  from  the  same  plants,  and 
looked  into  them,  their  inner  surfaces  were  quite  dry. 

I  then  examined  the  nectaries  of  Gymnadenia  cono^psea 
(a  plant  ranked  by  some  botanists  as  a  true  Orchis) 
and  of  Habenaria  hifolia,  which  are  always  full  of  nectai 
up  to  one-third  or  two-thirds  of  their  length.  The 
inner  membrane  presented  the  same  structure  and  was 
covered  with  papillae  as  in  the  foregoing  species ;  but 
there  was  a  plain  difference  in  the  inner  and  outer 
membranes  being  closely  united,  instead  of  being  in 
some  degree  separated  from  each  other  and  charged 
with  fluid.  I  was  therefore  led  to  conclude  that  insects 
penetrate  the  lax  inner  membrane  of  the  nectaries  of 
the  above-named  Orchids,  and  suck  the  copious  fluid 
between  the  two  membranes.  This  was  a  bold  hypo- 
thesis ;  for  at  the  time  no  case  was  known  of  insects 
penetrating  with  their  delicate  proboscides  even  the 
laxest  membrane.  But  I  have  now  heard  from  Mr. 
Trimen,  that  at  the  Cape  of  Good  Hope  moths  and 
butterflies  do  much  injury  to  peaches  and  plums  by 
puncturing  their  unbroken  skins.  In  Queensland 
Australia,  a  moth,  the  Oj)Mderes  fuUonica,  bores 
through  the  thick  rind  of  the  orange  with  its  wonder- 
ful proboscis,  provided  with  formidable  teeth.*  There 
is  therefore  not  the  least  difficulty  in  believing  that 
Lepidoptera  with  their  delicate  proboscides,  and  bees 

*  My  son  Francis  has  described       ♦  Q.     Journal     of    IMicroscopical 
and  figured    thitj    organ   iu   the       Science,'  vol.  xv.  1875,  p.  385. 


CuAP.  1.  SECRETION   OF   NECTAR.  41 

with  their  much  stronger  ones,  could  penetrate  with  ease 
the  soft  inner  membrane  of  the  nectaries  of  the  above- 
named  Orchids.  Dr.  H.  Muller  is  also  convinced*  that 
insects  puncture  the  thickened  bases  of  the  standard 
petals  of  the  Laburnum,!  and  perhaps  the  petals  of 
some  other  flowers,  so  as  to  obtain  the  included  fluid. 

The  various  kinds  of  bees  which  I  saw  vi^iiting  the 
flowers  of  Orchis  morio  remained  for  some  time  with 
their  proboscides  inserted  into  the  dry  neci;aries,  and 
I  distinctly  saw  this  organ  in  constant  movement.  I 
observed  the  same  fact  with  Empis  in  the  case  of  0. 
maculata ;  and  on  afterwards  opening  several  of  the 
nectaries,  I  occasionally  detected  minute  brown  specks, 
due  as  I  believe  to  the  punctures  made  some  time 
before  by  these  flies.  Dr.  H.  Miiller,  who  kis  often 
watched  bees  at  work  on  several  species  of  Oichis,  the 
nectaries  of  which  do  not  contain  any  free  nectar,  fully 
accepts  my  view.  J  On  the  other  hand,  Delpino  still 
maintains  that  Sprengel  is  right,  and  that  insects  are 
continually  deceived  by  the  presence  of  a  nectary, 
though  this  contains  no  nectar.  §  His  belief  is  founded 
chiefly  on  a  statement  by  Sprengel  that  insects  soon 
find  out  that  it  is  of  no  use  to  visit  the  nectaries  of 
these  orchids,  as  shown  by  their  fertilising  only  the 


*  *  Die  Befrnchtung,'  &c.  p.  235.  tinct  case,  Damely,  the  presence 
t  Treviranus  conliims  ('  Bot.  of  nectar  in  several  monocotyle- 
Zeitung,' 1863,  p.  10)  a  statement  donous  plants  (as  described  by- 
made  by  Salisbury,  tbat  when  the  Ad.  Brongniart  in  '  Bull.  Soc.  Bot. 
filaments  in  the  flowers  of  anotl.er  de  France,'  torn.  i.  1854,  p.  75) 
leiiuminous  plant,  Edwardsia,  fall  between  the  two  walls  '^feuillets) 
off,  or  when  they  aie  cautiously  which  form  the  divisions  of  the 
separated,  a  large  quantity  of  ovarium.  But  the  nectar  in  this 
sxceet  fluid  flows  from  tlie  points  case  is  conducted  to  the  outside 
of  separation ;  and  as  befureliaud  by  a  channel ;  and  the  secreting 
there  was  no  tiace  of  any  such  surface  is  homologically  an  ex- 
fluid,  it  must  have  been  contained,  terior  surface, 
as  Treviranus  remarks,  within  the  J  'Die  Befruchtung,'  &c.  p.  84. 
cellular  tissue.  I  may  add  an  ap-  §  'Ult.  Osservazioni  sulla  Di- 
parently  similar,  but   really  die-  cogamia,'  1875,  p.  121. 


42  OPHRL^.  Chap.  I 

lower  and  first  opened  flowers.  But  this  statement  is 
completely  contradicted  by  my  observations  previously 
given,  from  which  it  follows  that  very  many  of  the 
upper  flowers  are  fertilised ;  for  instance,  on  a  spike 
of  0.  loyramidalis  with  between  fifty  and  sixty  flowers, 
no  less  than  forty-eight  had  their  pollinia  removed. 
Nevertheless,  as  soon  as  I  learnt  that  Delpino  still  be- 
lieved in  Sprengel's  view,  I  selected  during  the  un- 
favourable season  of  1875  six  old  spikes  of  0.  maculata, 
and  divided  each  into  halves,  so  as  to  observe  whether 
many  more  capsules  were  produced  by  the  lower  than 
by  the  upper  half.  This  certainly  was  not  always  the 
case ;  for  in  some  of  the  spikes  no  difference  could  be 
detected  between  them  ;  in  others  there  were  more  cap- 
sules in  the  lower,  while  in  others  there  were  more  in 
the  upper  half.  A  spike  of  0.  ])yramidalis  examined 
in  the  same  manner  produced  twice  as  many  capsules 
in  the  upper  as  in  the  lower  half.  Bearing  in  mind 
these  facts  and  others  before  given,  it  appears  to  me 
incredible  that  the  same  insect  should  go  on  visiting 
flower  after  flower  of  these  Orchids,  although  it  never 
obtains  any  nectar.  Insects,  or  at  least  bees,  are  by 
no  means  destitute  of  intelligence.  They  recognise 
from  a  distance  the  flowers  of  the  same  species,  and 
keep  to  them  as  long  as  they  can.  When  humble- 
bees  have  bitten  holes  through  the  corolla,  as  they 
often  do,  so  as  to  reach  the  nectar  more  easily,  hive- 
bees  immediately  perceive  what  has  been  done  and 
take  advantage  of  the  perforations.  When  flowers 
having  more  than  a  single  nectary  are  visited  by  many 
bees,  so  that  the  nectar  is  exhausted  in  most  of  them, 
the  bees  which  afterwards  visit  such  flowers  insert 
their  proboscides  only  into  one  of  the  nectaries,  and 
if  they  find  this  exhausted,  they  instantly  pass  on  to 
another  flower.     Can  it  be  believed  that  bees  which 


Chap.  I.  SECRETION   OF   NECTAR.  43 

show  this  much  intelligence,  should  persevere  in 
visiting  flower  after  flower  of  the  above-named  Orchids, 
and  in  keeping  their  proboscides  in  constant  movement 
for  some  time  within  the  nectaries,  in  the  hope  of 
obtaining  nectar  which  is  never  present?  This,  as  I 
have  said,  seems  to  me  utterly  incredible. 

It  has  been  shown  how  numerous  and  beautiful  are 
the  contrivances  for  the  fertilisation  of  Orchids.  We 
know  that  it  is  of  the  highest  importance  that  the 
poUinia,  when  attached  to  the  head  or  proboscis  of  an 
insect,  should  be  fixed  symmetrically,  so  as  not  to  fall 
either  sideways  or  backwards.  We  know  that  in  the 
species  as  yet  described  the  viscid  matter  of  the  disc 
sets  hard  in  a  few  minutes  when  exposed  to  the  air, 
so  that  it  would  be  a  great  advantage  to  the  plant  if 
insects  were  delayed  in  sucking  the  nectar,  time  being 
thus  allowed  for  the  disc  to  become  immovably  affixed. 
It  is  manifest  that  insects  must  be  delayed  by  having 
to  bore  through  several  points  of  the  inner  membrane 
of  the  nectary,  and  to  suck  the  nectar  from  the  inter- 
cellular spaces ;  and  we  can  thus  understand  why  the 
nectaries  of  the  above-named  species  of  Orchis  do  not 
contain  free  nectar,  but  secrete  it  internally  between 
the  two  membranes. 

The  following  singular  relation  supports  this  view 
in  a  striking  manner.  I  have  found  free  nectar  within 
the  nectaries  of  only  five  British  species  of  Ophreae, 
namely,  in  Gymnadenia  conoi:)sea  and  alhida,  in 
Hahenaria  hifolia  and  clihrantlia,  and  in  Feristijlus  (or 
Habenaria)  viridis.  The  first  four  of  these  species  have 
the  viscid  surfaces  of  the  discs  of  their  pollinia  naked 
or  not  enclosed  within  pouches,  and  the  viscid  matter 
does  not  rapidly  set  hard  when  exposed  to  the  air,  as  if 
it  did,  it  would  immediately  have  been  rendered  use- 
less; and  this  shows  that  it  must  differ  in  chemical 


44  OPHKE^.  Chap.  I 

nature  from  that  in  the  foregoing  species  of  Orchis. 
But  to  make  sure  of  this  fact  I  removed  the  pollinia 
from  their  anther-cells,  so  that  the  upper  as  well  as  the 
under  surfaces  of  the  viscid  discs  were  freely  exposed 
to  the  air ;  in  Gymnadenia  conojysea  the  disc  remained 
sticky  for  two  hours,  and  in  Habenaria  chlorantlia  for 
more  than  twenty-four  hours.  In  Peristylus  viridis  the 
viscid  disc  is  covered  by  a  pouch-formed  membrane, 
but  this  is  so  minute  that  botanists  have  overlooked 
it.  I  did  not,  when  examining  this  species,  see  the 
importance  of  ascertaining  exactly  how  soon  the 
viscid  matter  set  hard ;  but  I  copy  from  my  notes 
the  words  written  at  the  time :  "  disc  remains  sticky 
for  some  time  when  removed  from  its  little  pouch." 

Now  the  meaning  of  these  facts  is  clear  :  as  the 
viscid  matter  of  the  discs  of  these  five  latter  species  is 
so  adhesive  that  it  serves  to  attach  the  pollinia  firmly 
to  the  insects  which  visit  the  flowers,  without  setting 
hard,  there  would  be  no  use  in  the  insects  being 
delayed  by  having  to  bore  holes  at  several  points 
through  the  inner  membrane  of  the  nectaries ;  and  in 
these  five  species,  and  in  these  alone,  we  find  copious 
nectar  ready  stored  for  rapid  suction  in  open  nectaries. 
On  the  other  hand,  whenever  the  viscid  matter  sets 
hard  by  exposure  for  a  short  time  to  the  air,  it  would 
manifestly  be  advantageous  to  the  plant,  if  insects 
were  delayed  in  obtaining  the  nectar ;  and  in  all  such 
species  the  nectar  is  lodged  within  intercellular  spaces, 
so  that  it  can  be  obtained  only  by  the  inner  mem- 
brane being  penetrated  at  several  points,  and  this  will 
require  time.  If  this  double  relation  is  accidental, 
it  is  a  fortunate  accident  for  the  plants ;  but  I  cannot 
believe  it  to  be  so,  and  it  appears  to  me  one  of  the 
most  wonderful  cases  of  adaptation  which  has  ever 
been  recorded. 


Chap.  IL  OPHEYS  MUSCIFEKA.  45 


CHAPTEK  II. 

OPHKE^ — continued. 

Fly  and  Spider  Ophrys — Bee  Ophrys,  apparently  adapted  for  perpetual 
eelf-fertilisatioQ,  but  with  paradoxical  contrivances  for  intercrossing 
— Herminium  monorehis,  attachment  of  the  pollinia  to  the  front  legs 
of  insects — Peristylus  viridis,  fertilisation  indirectly  effected  by  nectar 
secreted  from  three  parts  of  the  labellum— Gymnadenia  conopsea. 
and  other  species  —  Habenaria  or  Platanthera  chlorantha  and 
bifolia,  their  pulliuia  attached  to  the  eyes  of  Lepidoptera — Other 
species  of  Habenada — Bonatea — Disa — Summary  on  the  powers  of 
movement  in  the  pollinia. 

The  genus  Ophrys  differs  from  Orchis  chiefly  in 
having  separate  pouch-formed  rostella,*  instead  of 
the  two  being  confluent. 

In  Ophrys  muscifera,  or  the  Fly  Ophrys,  the  chief 
peculiarity  is  that  the  caudicle  of  the  pollinium 
(B,  fig.  5)  is  doubly  bent.  The  nearly  circular  piece 
of  membrane,  to  the  under  side  of  which  the  ball  of 
viscid  matter  adheres,  is  of  considerable  size,  and  forms 
the  summit  of  the  rostellum.     It  is  thus  freely  exposed 


*  It  is  not  correct  to  speak  of  fold  of  membrane  (see  B  in  fig.  1) 

two  robtella,  but  the  inaccuracy  projecting  between  the   bases   of 

m:'.y  be  forgiven  from  its  conve-  the    anther-cells.       This    folded 

nience.     The  rostellum  strictly  is  crest  (sometimes  converted  into  a 

a  single   organ,   formed   by   the  solid  ridge)  corresponds  with  the 

modification  of  the  dorsal  stigma  smooth  surface  lying  between  the 

aTid  pistil ;  so  that  in  ( iphrys  the  two  pouches  in  Opiirys,  and  owes 

two  pouches,  the  two  viscid  discs,  its  protuberant  and  fohlcd  condi- 

and  the  space  between  them  to-  tion  in  Orchis  to  the  two  pouches 

getlier  form   the   true  rosttllum.  having  been  brouglit  toirethtr  and 

Again,  iu  Orchis  I  l.ave  spoken  of  rendered   confluent.     Tliis   modi- 

the  pouch-formed   organ    as    tlie  tication    will    be   more   fully   ex* 

rostellum,  but  strictly  the  rostel-  plaineil  in  a  future  chapter, 
tun  includes  the  little  crest  or 


16 


OPHRE^. 


CuAP.  IL 


to  the  air,  instead  of  lying  almost  hidden  at  the  base  of 
the  anther,  as  in  Orchis,  and  thus  kept  damp.  Never- 
theless, when  a  pollinium  is  removed,  the  caudicle 
bends  downwards  in  the  course  of  about  six  minutes, 
Hud,  therefore,  at  an  unusually  slow  rate ;   the  upper 

Fig.  5. 


OrHRYS   MUSCIFERA,    OR   FlY    OpHRYS. 


a.      anthei.  s.     stigma. 

r,r.  rostelU.  I.     labellurn. 

A.  Flower  viewed  in  front :  the  two 
upper  petals  are  almost  cylin- 
drical and  hairy  :  the  two  ros- 
tella  stand  a  little  in  advance 


of  the  bases  of  the  anther-cells ; 
but  this  is  not  shown  from  the 
foreshortening  of  the  drawing. 
One  of  the  two  pollinia  removed 
from  its  anther-cell,  and  viewed 
laterally. 


er  d  still  remaining  curved.  I  formerly  thought  that 
it  was  incapable  of  any  movement,  but  have  been  con- 
vinced by  Mr.  T.  H.  Farrer  of  my  error.  The  ball  of 
viscid  matter  is  bathed  in  fluid  within  the  pouch  formed 
by  the  lower  half  of  the  rostellum,  and  this  is  necessary, 


Chap.  II.  OPHRYS  MUSCIFEEA.  47 

as  the  viscid  matter  quickly  sets  hard  when  exposed  to 
the  air.  The  pouch  is  not  elastic,  and  does  not  spring 
up  when  the  poUinium  is  removed.  Such  elasticity- 
would  have  been  useless,  as  there  is  here  a  separate 
pouch  for  each  viscid  disc ;  whereas  in  Orchis,  after 
one  pollinium  has  been  removed,  the  other  has  to 
be  kept  covered  up  and  ready  for  action.  Hence  it 
.'ippears  that  nature  had  been  so  economical  as  to  save 
even  superfluous  elasticity. 

The  pollinia  cannot,  as  I  have  often  proved,  be  shaken 
out  of  the  anther-cells.  That  insects  of  some  kind 
visit  the  flowers,  though  not  frequently,  and  remove 
the  pollinia,  is  certain,  as  we  shall  immediately  see. 
Twice  I  have  found  abundant  pollen  on  the  stigmas  of 
flowers,  in  which  both  pollinia  were  still  in  their  cells  ; 
and  no  doubt  this  might  have  been  much  oftener  ob- 
served. The  elongated  labellum  affords  a  good  landing- 
place  for  insects  :  at  its  base,  just  beneath  the  stigma, 
there  is  a  rather  deep  depression,  representing  the 
nectary  in  Orchis  ;  but  I  could  never  see  a  trace  of 
nectar  within  it ;  nor  have  I  ever  observed  any  insects 
approach  these  inconspicuous  and  scentless  flowers,  often 
as  I  have  watched  them.  There  is,  however,  on  each  side 
of  the  base  of  the  labellum  a  small  shining  projection, 
having  an  almost  metallic  lustre,  which  appears  curi- 
ously like  a  drop  of  fluid  or  nectar  ;  and  as  these  flowers 
are  only  visited  occasionally  by  insects,  Sprengel's  view 
of  the  existence  of  sham-nectaries  is  far  more  probable 
in  this  case  than  in  any  other  known  to  me.  On 
several  occasions  I  have  detected  minute  punctures  in 
these  protuberances,  but  I  was  not  able  to  decide  whether 
they  had  been  made  by  insects,  or  whether  superficial 
cells  had  spontaneously  burst.  Similar  shining  pro- 
tuberances are  present  on  the  labella  of  all  the  other 
species   of  Ophrys.     The  two    rostella  stand   not   far 


18 


OPHRE^. 


Chap.  II. 


apart,  and  project  over  the  stigma ;  and  if  any  object 
is  gently  pushed  against  one  of  them,  the  pouch  is 
depressed  and  the  viscid  ball  together  with  the  pol- 
linium  adheres  to  it  and  is  easily  removed. 

The  structure  of  the  flower  leads  me  to  believe  that 
small  insects  (as  we  shall  see  in  the  case  of  Listera) 
crawl  up  the  labellum  to  its  base,  and  that  in  bending 
their  heads  downwards,  so  as  to  puncture  and  suck,  or 
only  to  examine  one  of  the  small  shining  protuberances, 
they  push  against  the  pouch,  and  a  pollinium  is  attached 
to  their  heads  ;  they  then  fly  to  another  flower,  and 
there  bending  down  in  a  similar  manner,  the  attached 
and  doubly-bent  pollinium,  after  the  movement  of 
depression,  strikes  the  sticky  stigmatic  surface,  and 
leaves  pollen  on  it.  Under  the  next  species  we  shall 
see  reason  for  believing  that  the  natural  double  cur- 
vature of  the  caudicle  compensates  for  its  slight  power 
of  movement,  compared  with  that  in  all  the  species  of 
Orchis. 


In  1858,  17  plants,  bearing  57  flowers, j 
growing  near  each  other  were  examined/ 

In  1858,  25  plants  growing  in  another! 
spot,  and  bearing  65  flowers          .          .  j 

In  1860, 17  plants,  bearing  61  flowers 

In  1861,  4  plants  from  S.  Kent,  bearing  241 
flowers  (all  the  previous  plants  having) 
grown  in  N.  Kent)      .         .         .         .  j 

Total 

Number  of  Flowers. 

Both  Pollinia 

or  one  removed 

by  Insects. 

Both  Poll'nia 
In  their  Cells. 

30 

15 

28 

15 

27 

50 
33 

9 

88          1       119 

1 

That  insects  visit  the   flowers   of  the  Fly  Ophrys 
and  remove  the  pollinia,  though  not  efl'ectually  or  suifi- 


Chap.  II.  OPHRYS  MUSCIFERA.  49 

ciently,  the  following  cases  show.  During  several 
years  before  1858  I  occasionally  examined  some  flowers, 
and  found  that  only  thirteen  out  of  102  had  one  or 
both  pollinia  removed.  Although  at  the  time  I  re- 
corded in  my  notes  that  most  of  the  flowers  were 
partly  withered,  I  now  think  that  I  must  have  included 
many  young  flowers,  which  might  perhaps  have  been 
subsequently  visited ;  so  I  prefer  trusting  to  the  fol- 
lowing observations. 

We  here  see  that,  out  of  207  flowers  examined,  not 
half  had  been  visited  by  insects.  Of  the  eighty-eight 
flowers  visited,  thirty-one  had  only  one  pollinium  re- 
moved. As  the  visits  of  insects  are  indispensable  for 
the  fertilisation  of  this  Orchid,  it  is  surprising  (as  in 
the  case  of  Orchis  fusca)  that  the  flowers  have  not  been 
rendered  more  attractive  to  insects.  The  number  oi 
seed-capsules  produced  is  proportionably  even  less  than 
the  number  of  flowers  visited  by  insects.  The  year 
1861  was  extraordinarily  favourable  to  this  species  in 
this  part  of  Kent,  and  I  never  saw  such  numbers 
in  flower ;  accordingly  I  marked  eleven  plants,  which 
bore  forty-nine  flowers,  but  these  produced  only  seven 
capsules.  Two  of  the  plants  each  bore  two  capsules, 
and  three  other  plants  each  bore  one,  so  that  no  less 
than  six  plants  did  not  produce  a  single  capsule ! 
What  are  we  to  conclude  from  these  facts  ?  Are  the 
conditions  of  life  unfavourable  to  this  species,  though 
during  the  year  just  alluded  to  it  was  so  numerous  in 
some  places  as  to  deserve  to  be  called  quite  common  ? 
Could  the  plant  nourish  more  seed  ;  and  would  it  be  of 
any  advantage  to  it  to  produce  more  seed  ?  Why  does 
it  produce  so  many  flowers,  if  it  already  produces  a 
sufiiciency  of  seeds  ?  Something  seems  to  be  out  of 
order  in  its  mechanism  or  in  its  conditions.  We  shall 
presently  see  that  Ophrys  apifera  or  the  Bee  Ophrys 


50  OPHTvE^.  Chap.  II. 

presents  a  wonderful  contrast  in  every  flower  producing 
a  capsule. 

O^phys  aranifera,  or  the  Spider  Ophrys. — I  am  in- 
debted to  Mr.  Oxenden  for  some  spikes  of  this  rare 
Fig.  6.  species.     Whilst  the   poUinia 

remain  enclosed  within  their 
cells,  the  lower  part  of  the  cau- 
dicle  projects  up  in  a  straight 
line  from  the  viscid  disc,  and 
therefore  has  a  very  different 
'b'     ^  form  from  the  corresponding 

Ophiys  aranifera.  part  of  the  Caudiclc  of  0.  mUS- 

A.  Poiiinium  before  the  act  of  cifeva  ;  but  the  Upper  part  (A, 

B.  PoiiinkmiTfter'the  act  of  fig-  6)  is  a  little  bent  forward, 

depression.  that  is,  towards  the  labellum. 

The  point  of  attachment  of  the  caudicle  to  the  disc 
is  hidden  within  the  bases  of  the  anther-cells,  and 
is  thus  kept  damp ;  consequently,  as  soon  as  the 
pollinia  are  exposed  to  the  air,  the  usual  movement  of 
depression  takes  place,  and  they  sweep  through  an 
angle  of  about  ninety  degrees.  By  this  movement 
they  assume,  supposing  them  to  be  attached  to  an 
insect's  head,  a  position  exactly  adapted  for  striking 
the  stigmatic  surface,  which  is  situated,  relatively  to 
the  potich-formed  rostella,  rather  lower  down  in  the 
flower  than  in  the  Fly  Ophrys. 

I  examined  fourteen  flowers  of  the  Spider  Ophrys, 
several  of  which  were  partly  withered;  and  in  none 
were  both  pollinia,  and  in  three  alone  was  one  poiiinium 
removed.  Hence  this  species,  like  the  Fly  Ophrys, 
is  but  little  visited  by  insects  in  England.  In  parts 
of  Italy  it  is  even  less  visited,  for  Delpino  states* 
that  in  Liguria  hardly  one  flower  out  of  3000  sets  a 


*  '  Ult.  OBsert.  P.  Dico;;amia,'  &c.     Parte  i.  1868-69,  p.  1 77. 


Chap.  II.  OPIIRYS   ARACHNITES.  51 

capsule,  though  near  Florence  rather  more  capsules 
are  produced.  The  labellum  does  not  secrete  any 
nectar.  The  flowers,  however,  must  be  occasionally 
visited  and  fertilised  by  insects,  for  Delpino  found* 
pollen-masses  on  the  stigmas  of  some  flowers  which 
still  retained  both  their  own  pollinia. 

The  anther-cells  are  remarkably  open,  so  that  with 
some  plants  which  were  sent  me  in  a  box,  two  pair 
of  pollinia  fell  out,  and  stuck  by  their  viscid  discs 
to  the  petals.  Here  w^e  have  an  instance  of  the  first 
appearance  of  a  trifling  structure  which  is  of  not  the 
least  use  to  its  possessor,  but  becomes  when  a  little 
more  developed,  highly  beneficial  to  a  closely-allied 
species ;  for  although  the  open  state  of  the  anther-cells 
is  useless  to  the  Spider  Ophrys,  it  is  of  the  highest 
importance,  as  we  shall  presently  see,  to  the  Bee 
Ophrys.  The  flexure  of  the  upper  end  of  the  caudicle 
of  the  pollinium  is  of  service  to  the  Spider  and  Fly 
Ophrys,  by  aiding  the  pollen-masses,  when  carried  by 
insects  to  another  flower,  to  strike  the  stigma  ;  but  by 
an  increase  of  this  bend  together  with  increased  flexi- 
bility in  the  Bee  Ophrys,  the  pollinia  become  adapted 
for  the  widely  different  purpose  of  self-fertilisation. 

Oijilirys  arachnites. — This  form,  of  which  Mr.  Oxenden 
sent    me    several   living    specimens,    is         ^w.  7. 
considered  by  some  botanists  as  only  a 
variety  of  the  Bee  Ophrys,  by  others  as  a 
distinct  species.     The  anther-cells  do  not 
stand  so  high  above  the  stigma,  and  do 
not  overhang  it  so  much,  as  in  the  Bee 
Ophrys,  and  the  pollen  masses  are  more     PoiUnium  of 
elongated.      The   caudicle   is  only  two-  Ophrys arachnite 
thirds,  or  even  only  half  as  long  as  that  of  the  Bee 


'  Feroiidazi'iic  nelle  Piante  Antooarp 'O,'  1807.  p.  -0. 


52  OPHKE^.  Chap.  IL 

Ophiys,  and  is  miicli  more  rigid ;  the  upper  part  is 
naturally  curved  forward;  the  lower  part  undergoes 
the  usual  movement  of  depression,  when  the  pollinia 
are  removed  from  their  cells.  The  pollen-masses 
never  fall  spontaneously  out  of  their  cells.  This  plant, 
therefore,  differs  in  every  important  respect  from  0. 
aioifera,  and  seems  to  be  much  more  closely  allied  to 
0.  aranifera. 

Ophrijs  scolopax  of  Cavanilles. — This  form  inhabits 
the  north  of  Italy  and  the  south  of  France.  JMr. 
Moggridge  says*  that  at  Mentone  it  never  shows  any 
tendency  to  fertilise  itself,  whilst  at  Cannes  the  pollen- 
masses  naturally  fall  out  of  their  cells  and  strike  the 
stigma.  He  adds  :  "  This  material  difference  between 
the  two  is  accomplished  by  a  very  slight  bend  in  the 
anther-cells,  which  are  prolonged  into  a  beak  of  variable 
length,  in  the  case  of  the  self-fertilising  blossoms." 

Ophrijs  apifera, — The  Bee  Ophrys  differs  widely 
from  the  great  majority  of  Orchids  in  being  excellently 
constructed  for  fertilising  itself.  The  two  pouch -formed 
rostella,  the  viscid  discs,  and  the  position  of  the  stigma, 
are  nearly  the  same  as  in  tLe  other  species  of  Ophrys  ; 
but  the  distance  of  the  two  pouches  from  each  other, 
and  the  shape  of  the  pollen-masses  are  somewhat 
variable.!  The  caudicles  of  the  pollinia  are  remark- 
ably long,  thin,  and  flexible,  instead  of  being,  as 
in  all  the  other  Ophrese  seen  by  me,  rigid  enough 
to  stand  upright.  They  are  necessarily  curved 
forward  at  their  upper  ends,  owing  to  the  shape  of 
the  anther-cells  ;  and  the  pear-shaped  pollen-masses 
lie    embedded    high    above    and    directly   over   the 

*  'Journ.  Liiin.  Soc'  vol.  viii.  symmetrically  confluent  as  iu  tho 

1865,  p.  258.  genus  Orchis,  and  with  the  two 

t  I  once  found  a  single  flower  viscid  discs  likewise  confluent,  as 

on  the  summit  of  a  spike,  with  in  Orchis  pyramidalis  or  Jdrcina. 
the  two  rostella  as  completely  and 


Chap.  II. 


OPHRYS    APIFERA. 


53 


stigma.  The  anther-cells  naturally  open  soon  after 
the  flower  is  fully  expanded,  and  the  thick  ends  of 
the  pollen-masses  then  fall  out,  the  viscid  discs  still 
remaining  in  their  pouches.  Slight  as  is  the  weight 
of  the  pollen-masses,  yet  the  caudicles  are  so  thin  and 
quickly  become  so  flexible,  that  in  the  course  of  a  few 
hours  they  sink  down,  until  they  hang  freely  in  the  air 

Fig.  8. 


OpHRTS  APIFERA,  OR  BeE  OpHRYS. 


a.     anther. 

i.l.  label lum. 

A.  Side  view  of  flower,  with  the 
upper  sepal  and  the  two  upper 
petals  removed.  One  polliuium, 
with  its  disc  still  in  its  pouch, 
is  represented  as   jast   falling 


out  of  the  anther-cell;  and 
the  other  has  fiillen  almost  to 
its  full  extent,  opposite  to  the 
hidden  stigmatic  surface. 
B.  Pollinium  in  the  position  in 
which  it  lies  embedded. 


(see  lower  pollen-mass  in  fig.  A)  exactly  opposite  to 
and  in  front  of  the  stigmatic  surface.  In  this  position 
a  breath  of  air,  acting  on  the  expanded  petals,  sets 
the  flexible  and  elastic  caudicles  vibrating,  and  they 
almost  immediately  strike  the  viscid  stigma,  and, 
being  there  secured,  impregnation  is  effected.  To 
make  sure  that   no   other  aid  was  requisite,  though 


54  OPHRE^.  Chap.  IL 

the  experiment  was  superfluous,  I  covered  up  a  plant 
under  a  net,  so  that  the  wind,  but  no  insects,  could 
pass  in,  and  in  a  few  days  the  pollinia  became  attached 
to  the  stigmas.  But  the  pollinia  of  a  spike  kept  in 
water  in  a  still  room  remained  free,  suspended  in  front 
of  the  stigma,  until  the  flowers  withered. 

Robert  Brown  first  observed  that  the  structure  of  the 
Bee  Ophrys  is  adapted  for  self-fertilisation.*  When 
we  consider  the  unusual  and  perfectly-adapted  length, 
as  well  as  the  remarkable  flexibility  of  the  caudicles ; 
when  we  see  that  the  anther-cells  naturally  open,  and 
that  the  masses  of  pollen,  from  their  weight,  slowly 
fall  down  to  the  exact  level  of  the  stigmatic  surface, 
and  are  there  made  to  vibrate  by  the  slightest  breath 
of  wind  until  the  stigma  is  struck ;  it  is  impossible 
to  doubt  that  these  several  points  of  structure  and 
function,  which  occur  in  no  other  British  Orchid,  are 
specially  adapted  for  self- fertilisation. 

The  result  is  what  might  have  been  anticipated.  1 
have  often  noticed  that  the  spikes  of  the  Bee  Ophrys 
apparently  produced  as  many  seed-capsules  as  flowers ; 
and  near  Torquay  I  carefully  examined  many  dozen 
plants,  some  time  after  the  flowering  season ;  and  on 
all  I  found  from  one  to  four,  and  occasionally  five, 
fine  capsules,  that  is,  as  many  capsules  as  there  had 
been  flowers.  In  extremely  few  cases,  with  the  excep- 
tion of  a  few  deformities,  generally  on  the  summit  of 
the  spike,  could  a  flower  be  found  which  had  not  pro- 
duced a  capsule.  Let  it  be  observed  what  a  contrast 
this  species  presents  with  the  Fly  Ophrys,  which 
requires  insect  aid  for  its  fertilisation,  and  which  from 
forty-nine  flowers  produced  only  seven  capsules ! 

*  '  Transact.  Linn.  Soc'  vol.  common  to  the  genus.  As  far  aa 
xvi.  p.  740.  Brown  erroneously  the  fouf  British  species  are  con- 
believed  that  this  peculiarity  was       cerned,  it  applies  to  this  one  alone. 


Chap.  II.  OPHKYS  APIFERA.  55 

From  what  I  had  then  seen  of  otlier  Orchids,  I 
was  so  much  surprised  at  the  self-fertilisation  of  this 
species,  that  I  examined  during  many  years,  and  asked 
others  to  examine,  the  state  of  the  pollen-masses  in 
many  hundreds  of  flowers,  collected  in  various  parts  of 
England.  The  particulars  are  not  worth  detailing; 
but  I  may  give  as  an  instance,  that  Mr.  Farrer 
found  in  Surrey  that  not  one  flower  out  of  106 
had  lost  both  pollinia,  and  that  only  three  had  lost 
a  single  one.  In  the  Isle  of  Wight,  Mr.  More 
examined  136  flowers,  and  of  these  the  very  unusual 
number  of  ten  had  lost  both,  and  fourteen  had  lost 
one;  but  then  he  found  that  in  eleven  cases  the 
caudicles  had  been  gnawed  through  apparently  by 
snails,  the  discs  still  remaining  in  their  pouches ;  so 
that  the  pollinia  had  not  been  carried  away  by  insects. 
In  some  few  cases,  also,  in  which  I  found  the  pollinia 
removed,  the  petals  were  marked  with  the  slime  of 
snails.  Nor  must  we  forget  that  a  blow  from  a 
passing  animal,  and  possibly  heavy  storms  of  wind 
might  occasionally  cause  the  loss  of  one  or  both 
pollinia. 

During  most  years  the  pollen-masses  of  the  many 
hundred  flowers  which  were  examined,  adhered  with 
the  rarest  exceptions  to  the  stigma,  with  their  discs  still 
enclosed  within  the  pouches.  But  in  the  year  1868, 
from  some  cause  the  nature  of  which  I  cannot  conjecture, 
out  of  116  flowers  gathered  in  two  localities  in  Kent, 
seventy -five  retained  both  pollinia  in  their  cells ;  ten 
had  one  pollinium,  and  only  thirty-one  had  both 
adhering  to  the  stigma.  Long  and  often  as  I  have 
watched  plants  of  the  Bee  Ophrys,  I  have  never  seen 
one  visited  by  any  insect.*   Eobert   Brown  imagined 


•  Mr.  Gerard  E.  Smith,  in  his  'Catalogue  of  Plants  of  S.  Kent, 


66  OPHRE^.  Chap.  II. 

that  the  flowers  resembled  bees  in  order  to  deter  their 
visits,  but  this  seems  extremely  improbable.  The 
flowers  with  their  pink  sepals  do  not  resemble  an}'- 
British  bee,  and  it  is  probably  true,  as  I  have  heard  it 
said,  that  the  plant  received  its  name  merely  from  the 
hairy  labellum  being  somewhat  like  the  abdomen  of  a 
humble-bee.  We  see  how  fanciful  many  of  the  names 
are, — one  species  being  called  the  Lizard  and  another 
the  Frog  Orchis.  The  resemblance  of  0,  muscifera  to 
a  fly  is  very  much  closer  than  that  of  0.  apifera  to  a 
bee ;  and  yet  the  fertilisation  of  the  former  absolutely 
depends  on  and  is  effected  by  the  means  of  insects. 

All  the  foregoing  observations  relate  to  England, 
but  Mr.  Moggridge  made  similar  ones  on  the  Bee 
Ophrys  in  Northern  Italy  and  Southern  France,  as  did 
Treviranus*  in  Germany,  and  Dr.  Hooker  in  Morocco. 
We  may  therefore  conclude, — from  the  pollinia  spon- 
taneously falling  on  the  stigma — from  the  co-related 
structure  of  all  the  parts  for  this  purpose — and  from 
almost  all  the  flowers  producing  seed-capsules — that 
this  plant  has  been  specially  adapted  for  self-fertilisa- 
tion.    But  there  is  another  side  to  the  case. 

When  an  object  is  pushed  against  one  of  the 
pouches  of  the  rostellum,  the  lip  is  depressed,  and  the 
large  viscid  disc  adheres  firmly  to  it ;  and  when  the 
object  is  removed,  so  is  the  pollinium,  but  perhaps 
not  quite  so  readily  as  in  the  other  species  of 
Ophrys.  Even  after  the  pollen-masses  have  naturally 
fallen  out  of  their  cells  on  to  the  stigma,  their  removal 
can  sometimes  be  thus  effected.     As  soon  as  the  disc  is 


1S29,    p.   25,   says:    "Mr.   Piice  cannot  conjecture, 

has  frequently  witnessed  attacks  *  '  Dot.  Zeitung,'  1863,  p.  241. 

made  upon  the  Bee  Orchis  by  a  This  botanist  at  first  doubted  my 

bee,    simiLir    to     those    of    the  observations   on    Ophrys   apifera 

troublesome     Apis      muscorum."  and  aranifera,  but  has  since  fully 

What    this    sentence     means    I  confirmed  them. 


CuAP.  IL  OPHRYS   APIFERA.  57 

drawn  out  of  its  pouch  a  movement  of  depression 
commences,  by  which  the  pollinium  if  attached  to 
the  front  of  an  insect's  head  would  be  brought  into 
a  proper  position  for  striking  the  stigma.  When  a 
pollen-mass  is  placed  on  the  stigma  and  then  with- 
drawn, the  elastic  threads  by  which  the  packets  are 
tied  together  break,  and  leave  several  packets  on  the 
viscid  surface.  In  all  other  Orchids  the  meaning  of 
these  several  contrivances  is  unmistakably  clear — 
namely,  the  downward  movement  of  the  lip  of  the  ros- 
tellum  when  gently  pushed — the  viscidity  of  the  disc 
— the  depression  of  the  caudicle  as  soon  as  the  disc 
is  exposed  to  the  air — the  rupturing  of  the  elastic 
threads — and  the  conspicuousness  of  the  flower.  Are 
w^e  to  believe  that  these  adaptations  for  cross-fertilisa- 
tion in  the  Bee  Ophrys  are  absolutely  purposeless,  as 
would  certainly  be  the  case  if  this  species  has  always 
been  and  will  always  be  self-fertilised  ?  It  is,  however, 
just  possible  that  insects,  although  they  have  never 
been  seen  to  visit  the  flowers,  may  at  rare  intervals 
transport  the  poUinia  from  plant  to  plant,  during  such 
seasons  as  that  of  1868,  when  the  pollinia  did  not  all 
fall  out  of  the  anther- cells  so  as  to  reach  the  stigmas. 
The  whole  case  is  perplexing  in  an  unparalleled  degree, 
for  we  have  in  the  same  flower  elaborate  contrivances 
for  directly  opposed  objects. 

That  cross-fertilisation  is  beneficial  to  most  Orchids, 
we  may  infer  from  the  innumerable  structures  serving 
for  this  purpose  which  they  present ;  and  I  have 
elsewhere  shown  in  the  case  of  many  other  groups  of 
plants  *  that  the  benefits  thus  derived  are  of  high 
importance.  On  the  other  hand,  self-fertilisation  is 
manifestly  advantageous  in  as  far  as  it  ensures  a  full 

*  '  The  Effects  of  Cross  and  Self- Fertilisation  in  the  Vegetable 
Kingdom,'  1876. 

4 


58  OPHRE^.  Chap.  II. 

supply  of  seed;  and  we  have  seen  with  the  other 
British  species  of  Opnrys  which  cannot  fertilise  them- 
selves, how  small  a  proportion  of  their  flowers  produce 
capsules.  Judging  therefore  from  the  structure  of 
the  flowers  of  0.  apifera,  it  seems  almost  certain  that 
at  some  former  period  they  were  adapted  for  cross- 
fertilisation,  but  that  failing  to  produce  a  sufficiency 
of  seed  they  became  slightly  modified  so  as  to  fertilise 
themselves.  It  is,  however,  remarkable  on  this  view, 
that  none  of  the  parts  in  question  show  any  tendency 
to  abortion — that  in  the  several  and  distant  countries 
which  the  plant  inhabits,  the  flowers  are  still  con- 
spicuous, the  discs  still  viscid,  and  the  caudicles  still 
retain  the  power  of  movement  when  the  discs  are  ex- 
posed to  the  air.  The  metallic  points  at  the  base  of 
the  labellum  are  however  smaller  than  in  the  other 
species ;  and  if  these  serve  to  attract  insects,  this  dif- 
ference is  of  some  signification.  As  it  can  hardly  be 
doubted  that  0.  apifera  was  at  first  constructed  so  as 
to  be  regularly  cross-fertilised,  it  may  be  asked  will  it 
ever  revert  to  its  former  state ;  and  if  it  does  not  so 
revert,  will  it  become  extinct  ?  These  questions  cannot 
be  answered,  any  more  than  in  the  case  of  those  plants 
which  are  now  propagated  exclusively  by  buds,  stolons, 
&c.,  but  which  produce  flowers  that  rarely  or  never  set 
any  seed  ;  and  there  is  reason  to  believe  that  a  sexual 
propagation  is  closely  analogous  to  long-continued 
self-fertilisation. 

Finally  Mr.  Moggridge  has  shown  that  in  North 
Italy  Oplirys  apifera,  aranifera,  arachnites,  and  scolopax 
are  connected  by  so  many  and  such  close  intermediate 
links,*   that  all   seem  to  form   a  single   species    in 

♦  These  forms  are  illustrated  by  *  Verhandlungen     der     Kaiserl. 

beautiful    coloured    drawings  in  Leop.   Car.   Akad.'   (Nov.  Act.), 

tlie  '  Flora  of  Mentone,'  pi.  43  to  torn.  xxxv.  1869 
45:   and   in   his   memoir   in   the 


Chap.  II.  HERMINIUM   MONOKCHIS.  59 

accordance  with  the  belief  of  Linnaeus,  who  grouped 
them  all  together  under  the  name  of  Ophrys  insectifera, 
Mr.  Moggridge  further  shows  that  in  Italy  0.  aranifera 
flowers  first,  and  0.  apifera  last,  the  intermediate 
forms  at  intermediate  periods ;  and  according  to  Mr. 
Oxenden,  the  same  fact  holds  good  to  a  certain  extent 
in  Kent.  The  three  forms  which  inhabit  England  do 
not  seem  to  blend  into  one  another  as  in  Italy,  and  I 
am  assured  by  Mr.  Oxenden,  who  has  closely  attended 
to  these  plants  in  their  native  homes,  that  0.  aranifera 
and  ajpifera  always  grow  in  distinct  spots.  The  case 
therefore  is  an  interesting  one,  as  here  we  have  forms 
which  may  be  and  generally  have  been  ranked  as  true 
species,  but  which  in  North  Italy  have  not  as  yet  been 
fully  differentiated.  The  case  is  all  the  more  interest- 
ing, as  the  intermediate  forms  can  hardly  be  due  to 
the  crossing  of  0.  aranifera  with  ajnfera ;  this  latter 
species  being  regularly  self-fertilised  and  apparently 
never  visited  by  insects.  Whether  we  rank  the  several 
forms  of  Ophrys  as  closely  allied  species  or  as  mere 
varieties  of  the  same  species,  it  is  remarkable  that 
they  should  differ  in  a  character  of  such  physiological 
importances  as  the  flowers  of  some  being  plainly 
adapted  for  self-fertilisation,  whilst  the  flowers  of 
others  are  strictly  adapted  for  cross-fertilisation,  being 
utterly  sterile  if  not  visited  by  insects. 

Herminium  monorchis. — The  Musk  Orchis,  which  is 
a  rare  British  plant,  is  generally  spoken  of  as  having 
naked  glands  or  discs,  but  this  is  not  strictly  correct. 
The  disc  is  of  unusual  size,  nearly  equalling  the  mass 
of  pollen-grains  :  it  is  subtriangular,  with  one  side  pro- 
tuberant, and  somewhat  resembles  a  distorted  helmet 
in  shape  :  it  is  formed  of  hard  tissue  with  the  base 
hollowed  out,  and  viscid ;  the  base  resting  on  and 
being  covered  by  a  narrow  strip  of  membrane,  which  is 


60  OPHREJS.  CuAP.  II 

easily  pushed  away,  and  answers  to  the  pouch  in 
Orchis.  The  whole  upper  part  of  the  helmet  answers 
to  the  minute  oval  bit  of  membrane  to  which  the 
caudicle  of  Orchis  is  attached  and  which  in  Ophrys 
is  larger  and  convex.  When  the  lower  part  of  the 
helmet  is  moved  by  any  pointed  object,  the  point 
readily  slips  into  its  hollow  base,  and  is  there  held  so 
firmly  by  the  viscid  matter,  that  the  whole  helmet 
appears  adapted  to  stick  to  some  prominent  part  of  an 
insect's  body.  The  caudicle  is  short  and  very  elastic  ; 
it  is  attached  not  to  the  apex  of  the  helmet,  but  to  the 
hinder  end  ;  if  it  had  been  attached  to  the  apex,  the 
point  of  attachment  would  have  been  freely  exposed  to 
the  air  and  not  kept  damp ;  and  then  the  pollinium 
when  removed  from  its  cell  would  not  have  been 
quickly  depressed. 

This  movement  is  well  marked,  and  serves  to  bring- 
the  end  of  the  pollen-mass  into  a  proper  position  for 
striking  the  stigma.  The  two  viscid  discs  stand  wide 
apart.  There  are  two  transverse  stigmatic  surfaces, 
meeting  by  their  points  in  the  middle  ;  but  the  broad 
part  of  each  lies  directly  beneath  each  disc.  The 
labellum  is  remarkable  from  not  differing  much  in 
shape  from  the  two  upper  petals,  and  from  not  always 
occupying  the  same  position  in  reference  to  the  axis 
of  the  plant,  owing  to  the  ovarium  being  more  or  less 
twisted.  This  state  of  the  labellum  is  intelligible,  for 
as  we  shall  see,  it  does  not  serve  as  a  landing-place  for 
insects.  It  is  upturned,  and  together  with  the  two 
other  petals  makes  the  whole  flower  in  some  degree 
tubular.  At  its  base  there  is  a  hollow  so  deep  as 
almost  to  deserve  to  be  called  a  nectary ;  but  I  could 
not  perceive  any  nectar,  which,  as  I  believe,  remains 
enclosed  in  the  intercellular  spaces.  The  flowers  are 
very  small  and  inconspicuous,  but  emit  a  strong  honey- 


Chap.  II.  HERMINIUM   MONORCHIS.  61 

like  odour.  They  seem  highly  attractive  to  insects ;  in 
a  spike  with  only  seven  flowers  recently  open,  four  had 
both  poUinia,  and  one  had  a  single  pollinium  removed. 
When  the  first  edition  of  this  book  appeared  I  did 
not  know  how  the  flowers  were  fertilised,  but  my  son 
George  has  made  out  the  whole  process,  which  is 
extremely  curious  and  differs  from  that  in  any  other 
Orchid  known  to  me.  He  saw  various  minute  insects 
entering  the  flowers,  and  brought  home  no  less  than 
twenty-seven  specimens  with  pollinia  (generally  with 
only  one,  but  sometimes  with  two)  attached  to  them. 
These  insects  consisted  of  minute  Hymenoptera  (of 
which  Tetrasticlius  diaphantus  was  the  commonest), 
of  Diptera  and  Coleoptera,  the  latter  being  MaltJiodes 
hrevicollis.  The  one  indispensable  point  appears  to 
be  that  the  insect  should  be  of  very  small  size,  the 
largest  being  only  the  -^  of  an  inch  in  length.  The 
pollinia  were  always  attached  to  the  same  place, 
namely,  to  the  outer  surface  of  the  femur  of  one  of  the 
front  legs,  and  generally  to  the  projection  formed  by 
the  articulation  of  the  femur  with  the  coxa.  The 
cause  of  this  peculiar  mode  of  attacliment  is  suffici- 
ently clear  :  the  middle  part  of  the  labellum  stands  so 
close  to  the  anther  and  stigma,  that  insects  always  enter 
the  flower  at  one  corner,  between  the  edge  of  the 
labellum  and  one  of  the  upper  petals ;  they  also  almost 
always  crawl  in  with  their  backs  turned  directly  or 
obliquely  towards  the  labellum.  My  son  saw  several 
which  began  to  crawl  into  the  flowers  in  a  different 
position ;  but  they  came  out  and  changed  their  posi- 
tion. Standing  in  either  corner  of  the  flower,  with 
their  backs  turned  towards  the  labellum,  they  insert 
their  heads  and  fore  legs  into  the  short  nectary,  which 
is  seated  between  the  two  widely  separated  viscid  discs. 
I  ascertained  that  they  had  occupied  this  position  by 


62  OPHRE^.  Chap.  II. 

finding  three  dead  insects,  permanently  glued  to  the 
•Uses.  Whilst  sucking  the  nectar,  which  takes  two  or 
three  minutes,  the  projecting  joint  of  the  femur  stands 
under  the  large  helmet-like  viscid  disc  on  either  side  ; 
and  when  the  insect  retreats,  the  disc  exactly  fits  on 
and  is  glued  to  the  prominent  joint,  or  to  the  surface 
of  the  femur.  The  movement  of  depression  in  the 
caudicle  now  takes  place,  and  the  mass  of  pollen-grains 
then  projects  just  beyond  the  tibia ;  so  that  the  insect, 
when  entering  another  flower,  can  hardly  fail  to  ferti- 
lise the  stigma,  which  is  situated  directly  beneath  the 
disc  on  either  side. 

Fig.  9. 


Peristylus  viridis,  or  Frog  Orchis, 
Front  view  of  flower. 


a.  anther. 
s.  stigma. 
n.    orifice  of  central  nectary. 


n'u.  lateral  nectaries. 
/.       labellum. 


Peristylus  viridis. — This  plant,  which  bears  the  odd 
name  of  the  Frog  Orchis,  has  been  placed  by  many 
botanists  in  the  genus  Habenaria  or  Platanthera;  but 
as  the  discs  are  not  naked,  it  is  doubtful  whether  this 


Chap.  II.  PEKISTYLUS   VIRIDIS.  63 

classification  can  be  correct.  The  rostella  are  small 
and  widely  separated  from  each  other.  The  viscid 
matter  on  the  under  side  of  the  disc  forms  an  oval  ball 
which  is  enclosed  within  a  small  pouch.  The  upper 
membrane  to  which  the  caudicle  is  attached  is  of  large 
size  relatively  to  the  whole  disc,  and  is  freely  exposed 
to  the  air.  Hence  probably  it  is  that  the  pollinia  when 
removed  from  their  cases  do  not  become  depressed 
until,  as  Mr.  T.  H.  Farrer  has  observed,  twenty  or 
thirty  minutes  have  elapsed.  Owing  to  this  long 
interval,  I  formerly  thought  that  they  did  not  undergo 
any  movement  of  depression.  Supposing  a  pollinium 
to  be  attached  to  the  head  of  an  insect,  and  to  have 
become  depressed,  it  will  stand  at  the  proper  angle, 
vertically,  for  striking  the  stigma.  But  from  the 
lateral  position  of  the  anther-cells,  notwithstanding 
that  they  converge  a  little  towards  their  upper  ends, 
it  is  difficult  at  first  to  see  how  the  pollinia  when 
removed  by  insects  are  afterwards  placed  on  the 
stigma ;  for  this  is  of  small  size  and  is  situated  in  the 
middle  of  the  flower  between  the  two  widely  separated 
rostella. 

The  explanation  is,  1  believe,  as  follows.  The  base 
of  the  elongated  labellum  forms  a  rather  deep  hollow 
in  front  of  the  stigma,  and  in  this  hollow,  but  some  way 
in  advance  of  the  stigma,  a  minute  slit-like  orifice  (n) 
leads  into  a  short  bilobed  nectary.  Hence  an  insect, 
in  order  to  suck  the  nectar  with  which  the  nectary  is 
filled,  would  have  to  bend  down  its  head  in  front  of 
the  stigma.  The  labellum  has  a  medial  ridge,  which 
would  probably  induce  an  insect  first  to  alight  on 
either  side  ;  but,  apparently  to  make  sure  of  this, 
besides  the  true  nectary,  there  are  two  spots  (nn)  which 
secrete  drops  of  nectar  on  each  side  at  the  base  of 
the  labellum,  bordered  by  prominent  edges,  directly 


64  OPHRE.E.  CuAP.  II 

beneath  the  two  pouches.  Now  let  us  suppose  an  insect 
to  alight  on  one  side  of  the  labellum  so  as  first  to  lick 
up  the  exposed  drop  of  nectar  on  this  side ;  from  the 
position  of  the  pouch  exactly  over  the  drop,  it  would 
almost  certainly  get  the  pollinium  of  this  side  attached 
to  its  head.  If  it  were  now  to  go  to  the  mouth  of  the 
true  nectary,  the  pollinium  attached  to  its  head  from 
not  having  as  yet  become  depressed  would  not  touch 
the  stigma ;  so  that  there  would  be  no  self-fertilisation. 
The  insect  would  then  probably  suck  the  exposed  drop 
of  nectar  on  the  other  side  of  the  labellum,  and  would 
perhaps  get  another  pollinium  attached  to  its  head  ;  it 
would  thus  be  considerably  delayed  by  having  to  visit 
the  three  nectaries.  It  would  then  visit  other  flowers 
on  the  same  plant,  and  afterwards  flowers  on  a  distinct 
plant ;  and  by  this  time,  but  not  before,  the  pollinia 
will  have  undergone  the  movement  of  depression  and 
will  be  in  a  proper  position  for  effecting  cross-fertilisa- 
tion. It  thus  appears  that  the  secretion  of  nectar  at 
three  separate  points  of  the  labellum, — the  wide  dis- 
tance apart  of  the  two  rostella, — and  the  slow  down- 
ward movement  of  the  caudicle  without  any  lateral 
movement — are  all  correlated  for  the  same  purpose  of 
cross-fertilisation. 

To  what  extent  this  Orchis  is  frequented  by  insects, 
and  what  the  kinds  are,  I  do  not  know,  but  several  of 
the  flowers  on  two  spikes,  sent  me  by  the  Eev.  B.  S. 
Maiden,  had  a  single  pollinium  removed,  and  one 
flower  had  both  removed. 

We  now  come  to  two  genera,  namely,  Gymnadenia 
and  Habenaria  or  Platanthera,  including  four  British 
species,  which  have  uncovered  viscid  discs.  The  viscid 
matter,  as  before  remarked,  is  of  a  somewhat  different 
nature  from  that  in  Orchis,  Ophrys,  &c.,  and  does  not 


CUAK.  II. 


GYMNADENIA   CONOPSEA. 


65 


rapidly  set  hard.  Their  nectaries  are  stored  with  free 
nectar.  With  respect  to  the  uncovered  condition  of 
the  discs,  the  last  species,  or  Peristijlus  viridis,  is  in 
an  almost  intermediate  condition.  The  four  following 
species  compose  a  much  broken  series.  In  Gymna- 
denia  conopsea  the  vicid  discs  are  narrow  and  much 
elongated,  and  lie  close  together ;  in  G.  albida  they 
are  less  elongated,  but  still  approximate ;  in  Hdbenaria 
hifolia  they  are  oval  and  far  apart ;  and,  lastly,  in  II. 
ehlorantha  they  are  circular  and  much  farther  apart. 

Gymnadenia  conopsea. — In  general  appearance  this 
plant  resembles  pretty  closely  a  true  Orchis.  The 
poUinia  differ  in  having  naked,  narrow,  strap-shaped 

Fig.  10. 


GymXADENIA   CONOPSEA. 


A.   Pollinium,  before  the   act  of 
depression. 


B.  Pollinium,  after  the  act  of  de- 
pression, but  before  it  has 
closely  clasped  the  disc. 


discs,  which  are  as  long  as  the  caudicles  (fig.  10). 
When  the  pollinia  are  exposed  to  the  air  the  caudicle 
is  depressed  in  from  thirty  to  sixty  seconds ;  and  as 
the  posterior  surface  of  the  caudicle  is  slightly  hol- 
lowed out,  it  closely  clasps  the  upper  membranous 
surface  of  the  disc.  The  mechanism  of  this  movement 
will  be  described  in  the  last  chapter.  The  elastic 
threads  by  which  the  packets  of  pollen  are  bound  to- 
gether are  unusually  weak,  as  is  likewise  the  case  with 


66  OPHRE^.  Chap.  IL 

the  two  following  species  of  Habenaria :  this  was  well 
shown  by  the  state  of  specimens  which  had  been  kept 
in  spirits  of  wine.  This  weakness  apparently  stands  in 
relation  to  the  viscid  matter  of  the  discs  not  setting 
hard  and  dry  as  in  Orchis;  so  that  a  moth  with  a 
pollinium  attached  to  its  proboscis  might  be  enabled  to 
visit  several  flowers  without  having  the  whole  polli- 
nium dragged  off  by  the  first  stigma  which  was  struck. 
The  two  strap-shaped  discs  lie  close  together,  and  form 
the  arched  roof  of  the  entrance  into  the  nectary. 
They  are  not  protected,  as  in  Orchis,  by  a  lower  lip  or 
pouch,  so  that  the  structure  of  the  rostellum  is  simpler. 
When  we  come  to  treat  of  the  homologies  of  the  ros- 
tellum we  shall  see  that  this  difference  is  due  to  a 
small  change,  namely,  to  the  lower  and  exterior  cells 
of  the  rostellum  resolving  themselves  into  viscid 
matter  ;  whereas  in  Orchis  the  exterior  surface  retains 
its  early  cellular  or  membranous  condition. 

As  the  two  viscid  discs  form  the  roof  of  the  mouth  of 
the  nectary,  and  are  thus  brought  down  near  to  the 
labellum,  the  two  stigmas,  instead  of  being  confluent 
and  standing  beneath  the  rostellum,  as  in  most  of 
the  species  of  Orchis,  are  lateral  and  separate.  These 
stigmas  consist  of  protuberant,  almost  horn-shaped, 
processes  on  each  side  of  the  nectary.  That  their 
surfaces  are  really  stigmatic  I  ascertained  by  finding 
them  deeply  penetrated  by  a  multitude  of  pollen- 
tubes.  As  in  the  case  of  Orchis  'pyramidalis,  it  is  a 
pretty  experiment  to  push  a  fine  bristle  straight  into 
the  narrow  mouth  of  the  nectary,  and  to  observe  how 
certainly  the  narrow  elongated  viscid  discs,  forming 
the  roof,  stick  to  the  bristle.  When  the  bristle  is 
withdrawn,  the  pollinia  adhering  to  its  upper  side 
are  withdrawn ;  and  as  the  discs  form  the  sides  of 
the  arched   roof,  they  adhere  somewhat  to  the  sides 


Chap.  II.  GYMNADENIA   CONOPSEA.  67 

of  the  bristle.  They  then  quickly  become  depressed  so 
as  to  lie  in  the  same  line  with  the  bristle, — one  a  little 
on  one  side,  and  the  other  on  the  other  side ;  and  if 
the  bristle,  held  in  the  same  relative  position,  be  now 
inserted  into  the  nectary  of  another  flower,  the  two 
ends  of  the  pollinia  accurately  strike  the  two  protu- 
berant stigmatic  surfaces,  situated  on  each  side  of  the 
mouth  of  the  nectary. 

The  flowers  smell  sweet,  and  the  abundant  nectar 
always  contained  in  their  nectaries  seems  highly 
attractive  to  Lepidoptera,  for  the  pollinia  are  soon  and 
effectually  removed.  For  instance,  in  a  spike  with 
forty-five  open  flowers,  forty-one  had  their  pollinia 
removed,  or  had  pollen  left  on  their  stigmas:  in 
another  spike  with  fifty-four  flowers,  thirty-seven  had 
both  pollinia,  and  fifteen  had  one  pollinium,  removed ; 
so  that  only  two  flowers  in  the  whole  spike  had  neither 
pollinium  removed. 

My  son  George  went  at  night  to  a  bank  where 
this  species  grows  plentifully,  and  soon  caught  Plusia 
chrysitis  with  six  pollinia,  P.  gaytima  with  three,  Anaitis 
plagiata  with  five,  and  Triphmna  p-onuba  with  seven 
pollinia  attached  to  their  proboscides.  I  may  add 
that  he  also  caught  the  first-named  moth  in  my 
flower-garden,  with  the  pollinia  of  this  Orchis  attached 
to  its  proboscis,  but  with  all  the  pollen-grains  removed, 
although  the  garden  is  a  quarter  of  a  mile  distant  from 
any  spot  where  the  plant  grows.  Many  of  the  above 
moths  had  only  a  single  pollinium  attached,  somewhat 
laterally  to  their  proboscides ;  and  this  would  happen 
in  every  case,  unless  the  moth  stood  directly  in  front 
of  the  nectary  and  inserted  it  proboscis  exactly  be- 
tween the  two  discs.  But  as  the  labellum  is  rather 
broad  and  flat,  with  no  guiding  ridges  like  those  on 
the  labellum  of  Orchis  jjyramidalis,  there  is  notliing  to 


68  OPHEE^.  Chap.  II 

compel  motlis  to  insert  their  proboscides  symmetrically 
into  the  nectary,  and  there  would  be  no  advantage  in 
their  doing  so. 

Gifmnadeiiia  alhida. — The  structure  of  the  flower  of 
this  species  resembles  in  most  respects  that  of  the 
last ;  but,  owing  to  the  upturning  of  the  labellum,  it 
is  rendered  almost  tubular.  The  naked  elongated 
discs  are  minute  and  approximate.  The  stigmatic  sur- 
faces are  partially  lateral  and  divergent.  The  nectary 
is  short,  and  full  of  nectar.  Small  as  the  flowers  are, 
they  seem  highly  attractive  to  insects :  of  the  eighteen 
lower  flowers  on  one  spike,  ten  had  both,  and  seven 
had  one  pollinium  removed ;  on  some  older  spikes  all 
the  pollinia  had  been  removed,  except  from  two  or 
three  of  the  uppermost  flowers. 

Gymnadenia  odoratissima  is  an  inhabitant  of  the 
Alps,  and  is  said  by  Dr.  H.  Miiller*  to  resemble  in 
all  the  above  characters  G.  conopsea.  As  the  flowers, 
which  are  pale  coloured  and  highly  perfumed,  are  not 
visited  by  butterflies,  he  believes  that  they  are  fertilised 
exclusively  by  moths.  The  North  American  G.  tri- 
dentata,  described  by  Professor  Asa  Gray,t  differs  in  an 
important  manner  from  the  foregoing  species.  The 
anther  opens  in  the  bud,  and  the  pollen-grains,  which 
m  the  British  species  are  tied  together  by  very  weak 
threads,  are  here  much  more  incoherent,  and  some  in- 
variably fall  on  the  two  stigmas  and  on  the  naked 
cellular  tip  of  the  rostellum ;  and  this  latter  part, 
strange  to  say,  is  penetrated  by  the  pollen-tubes.  The 
flowers  are  thus  self-fertilised.  Nevertheless,  as  Pro- 
fessor Gray  adds, "  all  the  arrangements  for  the  removal 


♦   'Nature,*   Dec.  31,  1874,  p.  note  p.  200  ;  and  vol.  xxxvi.  18G3, 

109.  p.  293.     In   the   latter   paper  he 

t '  American  Journal  of  Science,'  adds  some  remarks  on  G.Jlava  and 

vol.  xxxiv.  1862,  p.  426,  and  foot-  nivea. 


Chap.  II. 


HABENARIA   CnLORANTHA. 


69 


of  the  pollinia  by  insects,  including  the  moYement  of 
depression,  are  as  perfect  as  in  the  species  which 
depend  upon  insect  aid."  Hence  there  can  be  little 
doubt  that  this  species  is  occasionally  cross-fertilised. 


Habenaria  CHLORAirrnA,  or  Butterfly  Orchis. 


a  a,  anther-cells. 

d.     disc  of  pollinium. 

8.      stigma. 

n.     nectary. 

n'.     orifice  of  nectary. 

/.       labellura. 

A.  Flower  viewed  in  front,  with  all 
the  sepals  and  petals  removed 
except  the  labellum  with  its 
nectary,  which  is  turned  to  one 
side. 


B.  A  pollinium.     (This  has  hardly 

a  sufficiently  elongated  appear- 
ance.) The  drum-like  pedicel 
is  hidden  behind  the  disc. 

C.  Diagram,      giving      a      section 

through  the  viscid  disc,  the 
drum-like  pedicel,  and  the 
attached  end  of  the  caudicle. 
The  viscid  disc  is  formed  of  an 
upper  membrane  with  a  layer 
of  viscid  matter  beneath. 


Habenaria  or  PJafanthera  clilorantlia, — The  pollinia 
of  the  Large  Butterfly  Orchis  differ  considerably  from 
those  of  any  species  hitherto  mentioned.      The   two 


70  OPHEE^.  Chap.  II. 

anther-cells  are  separated  from  each  other  by  a  wide 
space  of  connective  membrane,  and  the  pollinia  are 
enclosed  in  a  backward  sloping  position  (fig.  11).  The 
viscid  discs  front  each  other,  and  stand  in  advance  of 
the  stigmatic  surface.  In  consequence  of  their  forward 
position,  the  caudicles  and  pollen-masses  are  much 
elongated.  Each  viscid  disc  is  circular,  and,  in  the 
early  bud,  consists  of  a  mass  of  cells,  of  which  the 
exterior  layers  (answering  to  the  lip  or  pouch  in 
Orchis)  resolve  themselves  into  adhesive  matter.  This 
matter  has  the  property  of  remaining  adhesive  for  at 
least  twenty-four  hours  after  the  poUinium  has  been 
removed  from  its  cell.  The  disc,  externally  covered 
with  a  thick  layer  of  adhesive  matter  (see  fig.  C, 
which  stands  so  that  the  layer  of  viscid  matter  is  below) 
is  produced  on  its  opposite  and  embedded  side  into 
a  short  drum-like  pedicel.  This  pedicel  is  continuous 
with  the  membranous  portion  of  the  disc  and  is  formed 
of  the  same  tissue.  The  caudicle  of  the  pollinium  is 
attached  in  a  transverse  direction  to  the  embedded  end 
of  the  pedicel,  and  its  extremity  is  prolonged,  as  a  bent 
rudimentary  tail,  just  beyond  the  drum.  The  caudicle 
is  thus  united  to  the  viscid  disc  in  a  very  different 
manner,  and  in  a  plane  at  right  angles,  to  what  occurs 
in  the  other  British  Orchids.  In  the  short  drum- 
like pedicel,  we  have  a  small  development  of  the  long 
pedicel  of  the  rostellum,  which  is  so  conspicuous  in 
many  Yandeae,  and  which  connects  the  viscid  disc  with 
the  true  caudicles  of  the  pollinia. 

The  drum-like  pedicel  is  of  the  highest  importance, 
not  only  by  rendering  the  viscid  disc  more  prominent 
and  more  likely  to  stick  to  the  face  of  an  insect  whilst 
inserting  its  proboscis  into  the  nectary  beneath  the 
stigma,  but  on  account  of  its  power  of  contraction. 
The  pollinia  lie  inclined  backwards  in  their  cells  (see 


Chap.  IL  HABENARIA   CHLORANTHA.  71 

fig.  A),  above  and  some  way  on  each  side  of  the  stig- 
matic  surface ;  if  attached  in  this  position  to  the  head 
of  an  insect,  the  insect  might  visit  any  number  of 
flowers,  and  no  pollen  would  be  left  on  the  stigma. 
But  observe  what  takes  place  :  in  a  few  seconds  after  the 
inner  end  of  the  drum-like  pedicel  has  been  removed 
from  its  embedded  position  and  exposed  to  the  air,  one 
side  of  the  drum  contracts,  and  this  contraction  draws 
the  thick  end  of  the  poUinium  inwards,  so  that  the 
caudicle  and  the  viscid  surface  of  the  disc  are  no  longer 
parallel,  as  they  were  at  first,  and  as  they  are  repre- 
sented in  the  section,  fig.  G.  At  the  same  time  the 
drum  rotates  through  nearly  a  quarter  of  a  circle,  and 
this  moves  the  caudicle  downwards,  like  the  hand  of 
a  clock,  depressing  the  thick  end  of  the  pollinium  or 
mass  of  pollen-grains.  Let  us  suppose  the  right-hand 
disc  to  be  affixed  to  the  right  side  of  an  insect's  face, 
and  by  the  time  required  for  the  insect  to  visit 
another  flower  on  another  plant,  the  pollen-bearing 
end  of  the  pollinium  will  have  moved  downwards 
and  inwards,  and  will  now  infallibly  strike  the  viscid 
surface  of  the  stigma,  situated  in  the  middle  of  the 
flower  beneath  and  between  the  two  anther-cells. 

The  little  rudimentary  tail  of  the  caudicle  projecting 
beyond  the  drum-like  pedicel  is  an  interesting  point 
to  those  who  believe  in  the  modification  of  species  ; 
for  it  shows  us  that  the  disc  has  been  carried  a  little 
inwards,  and  that  primordially  the  two  discs  stood  even 
still  further  in  advance  of  the  stigma  than  they  do 
at  present.  We  thus  learn  that  the  parent-form  ap- 
proached in  this  respect  the  structure  of  that  extra- 
ordinary Orchid,  the  Bonatea  speciosa  of  the  Cape  of 
Good  Hope. 

The  remarkable  length  of  the  nectary,  containing 
much  free  nec;tar,  the  white  coloui  of  the  conspicuous 


72  OPIIKE^.  Chap.  II 

flowers,  and  tlie  strong  sweet  odour  emitted  by  them  at 
night,  all  show  tnat  this  plant  depends  for  its  fertilisa- 
tion on  the  larger  nocturnal  Lepidoptera.  I  have 
often  found  spikes  with  almost  all  the  pollinia  removed. 
From  the  lateral  position  and  distance  of  the  two 
viscid  discs  from  each  other,  the  same  moth  would 
generally  remove  only  one  pollinium  at  a  time ;  and 
in  a  spike  which  had  not  as  yet  been  much  visited, 
three  flowers  had  both  pollinia,  and  eight  flowers  had 
only  one  pollinium  removed.  From  the  position  of 
the  discs  it  might  have  been  anticipated  that  they 
would  adhere  to  the  side  of  the  head  or  face  of  moths ; 
and  Mr.  F.  Bond  sent  me  a  specimen  of  Hadena  dentina 
with  one  eye  covered  and  blinded  by  a  disc,  and  a 
specimen  of  Plusia  v.  aureum  with  a  disc  attached  to 
the  edge  of  the  eye.  Mr.  Marshall*  collected  twenty 
specimens  of  Gucidlia  umhratica  on  an  island  in  Der- 
went water,  separated  by  half-a-mile  of  water  from  any 
spot  where  H.  cldorantha  grew ;  nevertheless,  seven  of 
these  moths  had  the  pollinia  of  this  Orchid  afiixed  to 
their  eyes.  Although  the  discs  are  so  adhesive  that 
almost  all  the  pollinia  in  a  bunch  of  flowers  which  was 
carried  in  my  hand  and  thus  shaken  were  removed 
by  adhering  to  the  petals  or  sepals,  yet  it  is  certain 
that  moths,  probably  the  smaller  species,  often  visit 
these  flowers  without  removing  the  pollinia;  for  on 
examining  the  discs  of  a  large  number  of  pollinia 
whilst  still  in  their  cells  I  found  minute  Lepido- 
pterous  scales  glued  to  them. 

The  cause  of  the  flowers  of  various  kinds  of  Orchids 
being  constructed  so  that  the  pollinia  are  always 
afiixed  to  the  eyes  or  proboscides  of  Lepidoptera,  and 
to  the  naked  foreheads  or  proboscides  of  Hymenoptera, 


♦  '  Nature,'  Sept.  12,  1872,  p.  393. 


Chap.  II.  IIABENAEIA    BIFOLIA.  73 

no  doubt  is  that  the  viscid  discs  cannot  adhere  to 
a  scaly  or  very  hairy  surface;  the  scales  themselves 
being  easily  detached.  Variations  in  the  structure  of 
the  flower  of  an  Orchid,  unless  they  led  to  the  viscid 
discs  touching  some  part  of  the  body  of  an  insect 
where  they  would  remain  firmly  attached,  would  be  of 
no  service,  but  an  injury  to  the  plant ;  and  consequently 
such  variations  would  not  be  preserved  and  perfected. 

Hahenaria  hifolia,  or  Lesser  Butterflij  Orchis. — I  am 
aware  that  this  form  and  the  last  are  considered  by 
Mr.  Bentham  and  by  some  other  botanists  as  mere 
varieties  of  one  another  ;  for  it  is  said  that  intermediate 
gradations  in  the  position  of  the  viscid  discs  occur. 
But  we  shall  immediately  see  that  the  two  forms 
differ  in  a  large  number  of  other  characters,  not  to 
mention  general  aspect  and  the  stations  inhabited,  with 
which  we  are  not  here  concerned.  Should  these  two 
forms  be  hereafter  proved  to  graduate  into  each  other, 
independently  of  hybridisation,  it  would  be  a  remarkable 
case  of  variation ;  and  I,  for  one,  should  be  as  much 
pleased  as  surprised  at  the  fact,  for  these  two  forms 
certainly  differ  from  one  another  more  than  do  most 
species  belonging  to  the  same  genus. 

The  viscid  discs  of  the  Lesser  Butterfly  Orchis  are 
oval,  and  face  each  other.  They  stand  far  closer 
together  than  in  the  last  species ;  so  much  so,  that  in 
the  bud,  when  their  surfaces  are  cellular,  they  almost 
touch.  They  are  not  placed  so  low  down  relatively  to 
the  mouth  of  the  nectary.  The  viscid  matter  is  of 
a  somewhat  different  chemical  nature,  as  shown  by 
its  much  greater  viscidity,  if  after  having  been  long 
dried  it  is  moistened,  or  after  being  kept  in  weak 
spirits  of  wine.  The  drum-like  pedicel  can  hardly  be 
said  to  be  present,  but  is  represented  by  a  longitudinal 
ridge,   truncated   at   the   end   where   the   caudicle   is 


OPHEE^. 


Chap.  IL 


Fig.  12. 


fore-shortened. 
A.  Disc  and  caudicle  of  //.  hi 
full  I,  seen  from  above. 


attached,  and  there  is  hardly  a  vestige  of  the  rudi- 
mentary tail.  In  fig.  12  the  discs  of  both  species, 
of  the  proper  proportional 
sizes,  are  represented  as  seen 
vertically  from  above.  The 
pollinia,  after  removal  from 
their  cells,  undergo  nearly  the 
same  movements  as  in  the  last 

B.  Disc  and  caudicle  of  H.  chlo-  .  t        i     J_^       n  ji 

rantha,  seen   from    above,    SpCClCS.        in     both    lorms    the 

with  tiie  drum-like  pedicel  movement  is  wcll  showu  by 
removing  a  pollinium  by  the 
thick  end  with  a  pair  of  pin- 
cers, and  holding  it  under  the  microscope,  when  the 
plane  of  the  viscid  disc  will  be  seen  to  move  through 
an  angle  of  at  least  forty-five  degrees.  The  caudicles 
of  the  ]^esser  Butterfly  Orchis  are  relatively  very  much 
shorter  than  in  the  other  species;  the  little  packets 
of  pollen  are  shorter,  whiter,  and,  in  a  mature  flower, 
separate  much  more  readily  from  one  another.  Lastly, 
the  stigmatic  surface  is  differently  shaped,  being  more 
plainly  tripartite,  with  two  lateral  prominences,  situ- 
ated beneath  the  viscid  discs.  These  prominences 
contract  the  mouth  of  the  nectary,  making  it  sub- 
quadrangular.  Hence  I  cannot  doubt  that  the  Larger 
and  Lesser  Butterfly  Orchids  are  distinct  species, 
masked  by  close  external  similarity.* 

As   soon   as   I   had   examined  the  present  species. 


*  Afconling  to  Dr.  H.  Miiller, 
ITabenaria  or  Platanthera  bifoUa 
of  Enslish  authors  is  the  P.  sol- 
stitialis  of  Boenuinghausen ;  and 
lie  fully  agrees  with  me  that  it 
must  be  ranked  as  specifically 
distinct  from  P.  chlorantlia.  Dr. 
MuUer  states  tl)at  this  latter 
species  is  connected  by  a  series 
of  gradalions  witJi  another  form 


which  in  Germany  is  called  P. 
hifolia.  He  gives  a  very  full  and 
interesting  account  of  the  varia- 
bility of  these  three  forms  of 
Platanthera,  and  of  their  structure 
in  relation  to  their  manner  of  fer- 
tilisation :  'Verhandl.  d.  Nat. 
Verein.  f.  Pr.  Eh.  u.  Westfal' 
Jahrg.  XXV.  III.  Folge,  v.  Bd.  pp. 
36-38. 


Chap.  II.  rLATANTHERA.  75 

I  felt  convinced,  from  the  position  of  the  viscid  discs, 
that  it  would  be  fertilised  in  a  different  manner  from 
the  Larger  Butterfly  Orchis;  and  now,  owing  to  the 
kindness  of  Mr.  F.  Bond,  I  have  examined  two  moths, 
namely,  Agrotis  segetum  and  Anaitis  plagiata,  one  with 
three  pollinia,  and  the  other  with  five  pollinia,  attached, 
not  to  the  eyes  and  side  of  the  face  as  in  the  last 
species,  but  to  the  base  of  the  proboscis.  I  may 
remark  that  the  pollinia  of  these  two  species  of  Habe- 
naria,  when  attached  to  moths,  can  be  distinguished  at 
a  glance. 

Professor  Asa  Gray  has  described*  the  structure  of 
no  less  than  ten  American  species  of  Platanthera. 
jMost  of  them  reseml^le  in  their  manner  of  fertilisation 
the  two  British  species ;  but  some  of  the  species,  in 
which  the  viscid  discs  do  not  stand  far  apart,  have 
curious  contrivances,  such  as  a  channelled  labellum, 
lateral  shields,  &c.,  compelling  moths  to  insert  their 
proboscides  directly  in  front.  P.  hooJceri,  on  the  other 
hand,  differs  in  a  very  interesting  manner :  the  two 
viscid  discs  stand  widely  separated  from  each  other ; 
consequently  a  moth,  unless  of  gigantic  size,  would  be 
able  to  suck  the  copious  nectar  without  touching  either 
disc  ;  but  this  risk  is  avoided  in  the  following  manner : 
— the  central  line  of  the  stigma  is  prominent,  and  the 
labellum,  instead  of  hanging  down,  as  in  most  of  the 
other  species,  is  curved  upwards,  so  that  the  front  of 
the  flower  is  made  somewhat  tubular  and  is  divided 
into  halves.  Thus  a  moth  is  compelled  to  go  to  the 
one  or  other  side,  and  its  face  will  almost  certainly  be 
brought  into  contact  with  one  of  the  discs.  The  drum 
of  the  poUinium,  when  removed,  contracts  in  tlie 
same  manner  as  I  have  described  under  P.  chlorantha. 


♦'American  Journal   of  Science,'  vol.   xxxiv.    18G2,  pp.    113,  25f), 
and  424,  and  vol.  xxxvi.  1S63,  p.  292. 


76  OPHEE.E.  Chap.  II. 

Professor  Gray  lias  seen  a  butterfly  (Nisoniades)  from 
Canada  with  a  pollinium  of  this  species  attached  to 
each  eye.  In  the  case  of  P.  flava,  moths  are  compelled 
in  a  different  manner  to  enter  the  nectary  on  one  side. 
A  narrow  but  strong  protuberance,  rising  from  the  base 
of  the  labellum,  projects  upwards  and  backwards,  so 
as  almost  to  touch  the  column ;  thus  the  moth,  being 
forced  to  go  to  either  side,  is  almost  sure  to  withdraw 
one  of  the  viscid  discs.  P.  hijjyerborea  and  dilatata 
have  been  regarded  by  some  botanists  as  varieties  of 
the  same  species;  and  Professor  Asa  Gray  says  that 
he  was  formerly  tempted  to  come  to  the  same  con- 
clusion ;  but  on  closer  examination  he  finds,  besides 
other  characters,  a  remarkable  physiological  difference, 
namely,  that  P.  dilatata,  like  its  congeners,  requires 
insect  aid  and  cannot  fertilise  itself;  whilst  in  P. 
hyperlorea  the  pollen-masses  commonly  fall  out  of  the 
anther-cells  whilst  the  flower  is  very  young  or  in  bud, 
and  thus  the  stigma  is  self-fertilised.  Nevertheless,  the 
various  structures  adapted  for  crossing  are  still  present.* 
The  genus  Bonatea  is  closely  allied  to  Habenaria, 
and  includes  plants  having  an  extraordinary  structure. 
Bonatea  speciosa  is  an  inhabitant  of  the  Cape  of  Good 
Hope,  and  has  been  carefully  described  by  Mr.  Trimen  ;t 
but  it  is  impossible  to  explain  its  structure  without 
drawings.  It  is  remarkable  from  the  manner  in  which 
the  two  stigmatic  surfaces,  as  well  as  the  two  viscid 
discs,  project  far  out  in  front  of  the  flower,  and  from 
the  complex  nature  of  the  labellum,  which  consists  of 
seven,  or  probably  of  nine   distinct   parts   all   fused 


*  Mr.  J.  Mansel  Weale  has  de-  pollinia  not  uudei-froing  any  move- 
scribed  ('  Journ.  Lin.   Soc.    Bot.*  nient  or  change  of  position  when 
vol.  xiii.  1871,  p.  47)  the  method  of  removed  from  their  cases. 
fertilisation  of  two  South  African  f  '  Journ.  Linn.  Soc.  Bot.*  voL 
species    of    Habenaria  :     one    of  ix.  1865,  p.  156. 
these    is    remarkable    from    the 


CiiAP.  II.  iJONATEA    SPECIOSA-  77 

together.  As  in  Flatantliera  flava,  there  is  a  process 
at  the  base  of  the  labellum  which  compels  moths  to 
enter  the  flower  on  either  side.  The  nectary,  accord- 
ing to  Mr.  Trimen  and  Mr.  J.  Mansel  Weale,  does  not 
contain  free  nectar ;  but  the  latter  author  believes 
that  the  tissue  of  which  it  is  composed  tastes  sweet,  so 
that  moths  probably  penetrate  it  for  the  sake  of  the 
intercellular  fluid.  The  pollinia  are  of  astonishing 
length,  and  when  removed  from  their  cases  hang  down 
merely  from  the  weight  of  the  pollen-masses,  and  if 
attached  to  the  head  of  an  insect  would  be  in  a  proper 
position  for  adhering  to  the  stigma.  Mr.  Weale  has 
likewise  described  some  other  South  African  species 
of  Bonatea.*  These  differ  from  B.  speciosa  in  having 
their  nectaries  full  of  nectar.  He  found  a  small 
butterfly,  Fyrgus  elmo,  "  perfectly  embarrassed  by  the 
number  of  pollinia  of  this  Bonatea  attached  to  its 
sternum."  But  he  does  not  specify  whether  the 
sternum  was  naked  or  covered  with  scales. 

The  South  African  genera  Disa  and  Disperis  are 
placed  by  Lindley  in  two  sub-tribes  of  the  Ophrese. 
The  superb  flowers  of  Disa  grandiflora  have  been 
described  and  figured  by  Mr.  Trimen.t  The  posterior 
sepal,  instead  of  the  labellum,  is  developed  into  a  large 
nectary.  In  order  that  insects  may  reach  the  copiously 
stored  nectar,  they  must  insert  their  proboscides  on 
either  side  of  the  column;  and  in  accordance  with 
this  fact  the  viscid  discs  are  turned  outwards  in  an 
extraordinary  manner.  The  pollinia  are  crooked,  and 
when  removed  bend  downwards  from  their  own  weight, 
so  that  no  movement  is  necessary  for  placing  themselves 
in  a  proper  position.     Considering  the  large  supply  of 

•  *  Joum.  Linn.  Soc.  Bot.*  vol.  t  *  Journ.  Linn.  Soe.  Bot.'  vol. 

X.  p.  470.  vii.  1863,  p.  144. 


78  OPHRE^.  Chap.il 

nectar  and  that  the  flowers  are  very  conspicuous,  it 
is  remarkable  that  they  are  rarely  visited  by  insects. 
Mr.  Trimen  wrote  to  me  in  1864  that  he  had  lately 
examined  seventy-eight  flowers,  and  only  twelve  of 
these  had  one  or  both  pollinia  removed  by  insects, 
and  only  five  had  pollen  on  their  stigmas.  He  does 
not  know  what  insects  occasionally  fertilise  the  flowers ; 
but  Mrs.  Barber  has  more  than  once  seen  a  large  fly, 
allied  to  Bombylius,  with  the  pollinia  oiBisa  polygnoides 
attached  to  the  base  of  its  proboscis.  Mr.  Weale  states* 
that  D.  macrantha  differs  from  D.  grandiflora  and  earnuta 
in  producing  plenty  of  seed,  and  is  remarkable  from 
often  fertilising  itself.  This  follows  from  "  a  very  slight 
jerk,  when  the  flower  is  fully  expanded,  sufficing  to 
eject  the  pollinia  from  their  widely  open  anther-cases, 
and  to  bring  them  into  contact  with  the  stigma. 
This  in  nature  is  not  unseldom  the  case,  as  I  have 
repeatedly  found  many  flowers  thus  fertilised."  He 
has,  however,  no  doubt  that  the  flowers  are  likewise 
cross-fertilised  by  nocturnal  insects.  He  adds  that 
D.  grandiflora  in  being  so  seldom  fertilised  by  insects 
off'ers  a  case  like  that  of  Oplirijs  muscifera ;  w^hilst 
D.  macrantha  in  being  often  self-fertilised  closely  cor- 
responds with  Ophrijs  apifera ;  but  this  latter  species 
seems  to  be  invariably  self-fertilised. 

Lastly,  Mr.  Weale  has  described,!  as  far  as  he  could 
make  out,  the  manner  in  which  a  species  of  Disperis 
is  fertilised  by  the  aid  of  insects.  It  deserves  notice 
that  the  labellum  and  two  lateral  sepals  of  this  plant 
secrete  nectar. 

We  have  now  finished  with  the  Ophre?e ;  but  before 
passing  on  to  the  following  tribes,  I  will  recapitulate 

*  '  Jonrn.  Linn.  Soc.  Bot.'  vol.  t  *  Jomn.  Linn    Soc.  Bot.*  vol. 

xiii.  1871.  p.  4.^.  xiii.  187L  p.  42. 


Chap.  II.  OPPREiE.  79 

the  chief  facts  with  respect  to  the  movements  of  the 
pollinia,  all  due  to  the  nicely  regulated  contraction  of 
that  small  portion  of  membrane  (together  with  the 
pedicel  in  the  case  of  Habenaria)  lying  between  the 
layer  or  ball  of  adhesive  matter  and  the  extremity  of 
the  caudicle.  In  a  few  cases,  however,  as  with  some 
of  the  species  of  Disa  and  Bonatea,  the  caudicles  when 
removed  from  their  cells  do  not  undergo  any  movement ; 
the  weight  of  the  pollen-masses  sufScing  to  depress 
them  into  a  proper  position.  In  most  of  the  species  of 
Orchis  the  stigma  lies  directly  beneath  the  anther-cells, 
and  the  pollinia  simply  move  vertically  downwards. 
In  Orchis  pyramidalis  there  are  two  lateral  and  inferior 
stigmas,  and  the  pollinia  move  downwards  and  outwards, 
diverging  to  the  proper  angle,  so  as  to  strike  the  two 
lateral  stigmas.  In  Gymnadenia  the  pollinia  move 
only  downwards,  but  they  are  adapted  for  striking  the 
lateral  stigmas,  by  being  attached  to  the  upper  lateral 
surfaces  of  the  proboscides  of  Lepidoptera.  In  Nigri- 
tella  they  move  upwards,  but  this  depends  merely  on 
their  being  always  affixed  to  the  lower  side  of  the 
proboscis.  In  Habenaria  the  stigmatic  surface  lies 
beneath  and  between  the  two  widely-separated  anther- 
cells,  and  the  pollinia  here  converge,  instead  of  diverg- 
ing as  in  Orchis  pyramidalis,  and  likewise  move  down- 
wards. A  poet  might  imagine  that  whilst  the  pollinia 
were  borne  through  the  air  from  flower  to  flower, 
adhering  to  an  insect's  body,  they  voluntarily  and 
eagerly  placed  themselves  in  that  exact  position,  in 
which  alone  they  could  hope  to  gain  their  wish  and 
perpetuate  their  race. 


80  AEETHUSE^  Chap.  IIL 


CHAPTEK  IIL 

AEETHUSE^. 

Cephalanthera  grandiflora ;  rostellum  aborted ;  early  penetration  of  the 
pollen-tubes;  case  of  imperfect  self-fertilisation ;  cross-fertilisation 
effected  by  insect^i  which  gnaw  the  labellum — Cephalanthera  ensi- 
folia — Pogonia— Pterostylis  and  other  Austialian  orchids  with  the 
labellum  sensitive  to  a  touch — Vanilla— Sobraha. 

Cephalanthera  grandiflora, — This  Orchid  is  remark- 
able from  not  possessing  a  rostellum,  which  is  so 
eminently  characteristic  of  the  order.  The  stigma  is 
large,  and  the  anther  stands  above  it.  The  pollen 
is  extremely  friable  and  readily  adheres  to  any  object. 
The  grains  are  tied  together  by  a  few  weak  elastic 
threads ;  but  they  are  not  cemented  together,  so  as  to 
form  compound  pollen-grains,  as  in  almost  all  other 
Orchids.*  In  this  latter  character  and  in  the  complete 
abortion  of  the  rostellum  we  have  evidence  of  degrada- 
tion ;  and  Cej)halanthera  appears  to  me  like  a  degraded 
Epipactis,  a  member  of  the  Neottese,  to  be  described  in 
the  next  chapter. 

The  anther  opens  whilst  the  flower  is  in  bud  and 
partly  expels  the  pollen,  which  stands  in  two  nearly 
free  upright  pillars,  each  nearly  divided  longitudinally 
into  halves.  These  subdivided  pillars  rest  against  or 
even  overhang  the  upper  square  edge  of  the  stigma, 
which  rises  to  about  one- third  of  their  height  (see  front 


♦  This  separation  of  the  grains  by  Lindley  in  hi's  magnificent 
was  ob.served,  and  is  represented,  '  Illustrations  of  Orchidaceous 
by  Bauer  in  the  plate  published       Plants.' 


Chap.  III.         CEPHALANTHERA   GRANDIFLORA. 


81 


view  B,  and  side  view  C,  in  fig.  13).  Whilst  the  flower 
is  still  in  bud,  the  pollen-grains  which  rest  against  the 
upper  sharp  edge  of  the  stigma  (but  not  those  in  the 
upper  or  lower  parts  of  the  mass)  emit  a  multitude  of 


B 


Cephalanthera.  graxdiflora. 


anther;  in  the  front  view,  B, 
the  two  cells  with  the  included 
pollen  are  seen. 

one  of  the  two  lateral  rudimen- 
tary anthers,  or  auricles. 

masses  of  pollen. 

stigma. 

distal  portion  of  the  labellum. 


A.  Oblique  view  of  perfect  flower, 
when  fully  expanded. 

B.  Front  view  of  column,  with  all 
the  petals  and  sepals  removed. 

C.  Side  view  of  column,  with  all  the 
sepals  and  petals  removed  ;  the 
narrow  pillars  of  pollen  (p) 
between  the  anther  and  stigma 

]  can  just  be  seen. 

tubes  ;  and  these  deeply  penetrate  the  stigmatic  tissue. 
After  this  period  the  stigma  bends  a  little  forward,  and 
the  result  is  that  the  two  friable  pillars  of  pollen  are 
drawn  a  little  forward  and  stand  almost  completely  free 

4147 


82  ARETliUSE^.  Chap.  IIL 

from  the  anther-cells,  being  tied  to  the  edge  of  the 
stigma  and  supported  by  the  penetration  of  the  pollen- 
tubes.  AVithout  this  support  the  pillars  would  soon  fall 
down. 

The  flower  stands  upright,  with  the  lower  part  of 
the  labellum  turned  up  parallel  to  the  column  (fig.  A). 
The  tips  of  the  lateral  petals  never  become  separated  ;  * 
so  that  the  pillars  of  pollen  are  protected  from  the 
wind,  and  as  the  flower  stands  upright  they  do  not 
fall  down  from  their  own  weight.  These  are  points  of 
much  importance  to  the  plant,  as  otherwise  the  pollen 
would  have  been  blown  or  fallen  down  and  been 
wasted.  The  labellum  is  formed  of  two  portions ;  when 
the  flower  is  mature,  the  small  triangular  distal  portion 
turns  down  at  right  angles  to  the  basal  portion ;  and 
thus  offers  a  small  landing-place  for  insects  in  front 
of  the  triangular  entrance,  situated  half-way  up  the 
almost  tubular  flower.  After  a  short  time,  as  soon  as 
the  flower  is  fully  fertilised,  the  small  distal  portion 
of  the  labellum  rises  up,  shuts  the  triangular  door,  and 
again  perfectly  encloses  the  organs  of  fructification. 

Although  I  have  often  searched  for  nectar  within  the 
cup  of  the  labellum,  I  have  never  found  even  a  trace. 
The  terminal  portion  of  the  labellum  is  frosted  with 
globular  papillae  of  an  orange  colour,  and  within  the 
cup  there  are  several  transversely  wrinkled,  longi- 
tudinal ridges  of  a  darker  orange  tint.  These  ridges 
are  often  gnawed  by  some  animal,  and  I  have  found 
minute,  bitten-off  fragments  lying  within  the  base  of  the 
cup.  In  the  summer  of  1862  the  flowers  were  visited 
less  frequently  by  insects  than  is  usual,  as  shown  by 
the  unbroken  state  of  the  pollen-masses  ;  nevertheless, 


*  Bauer    fif^nres    the    flowers      say  is  that  I  have  not  seen  them 
much  more  widely  expande  1  than       in  this  condition. 
is  here  represented  :  all  that  I  can 


Chaf.  III.         CEPHALANTHERA    GEANDIFLOKA.  83 

out  of  seventeen  flowers  which  were  examined  one  day^ 
five  had  their  ridges  gnawed,  and  on  the  next  day, 
seven  out  of  nine  other  flowers  were  in  this  state.  As 
there  was  no  appearance  of  slime,  I  do  not  believe 
that  they  had  been  attacked  by  slugs;  but  whether 
they  had  been  gnawed  by  winged  insects,  which  alone 
would  be  effectual  for  cross-fertilisation,  I  know  not. 
The  ridges  had  a  taste  like  that  of  the  labellum  of 
certain  Vandeae,  in  which  tribe  (as  we  shall  hereafter 
see)  this  part  of  the  flower  is  often  gnawed  by  insects. 
Cephalanthera  is  the  only  British  Orchid,  as  far  as  I 
have  observed,  which  attracts  insects,  by  thus  ofiering 
to  them  solid  food. 

The  early  penetration  of  the  stigma  by  a  multitude 
of  pollen-tubes,  which  were  traced  far  down  the  stigmatic 
tissue,  apparently  gives  us  another  case,  like  that  of  the 
Bee  Ophrys,  of  perpetual  self-fertilisation.  I  was  much 
surprised  at  this  fact,  and  asked  myself :  Why  does  the 
distal  portion  of  the  labellum  open  for  a  short  period  ? 
what  is  the  use  of  the  great  mass  of  pollen  above  and 
below  that  layer  of  grains,  the  tubes  of  which  alone 
penetrate  the  upper  edge  of  the  stigma  ?  The  stigma 
has  a  large  flat  viscid  surface ;  and  during  several  years 
I  have  almost  invariably  found  masses  of  pollen  adher- 
ing to  its  surface,  and  the  friable  pillars  by  some  means 
broken  down.  It  occurred  to  me  that,  although  the 
flowers  stand  upright,  and  the  pillars  are  well  pro- 
tected from  the  wind,  yet  that  the  pollen-masses  might 
ultimately  topple  over  from  their  own  weight,  and  so 
fall  on  the  stigma,  thus  completing  the  act  of  self-fer- 
tilisation. Accordingly,  I  covered  with  a  net  a  plant 
having  four  buds,  and  examined  the  flowers  as  soon  as 
they  had  withered  ;  the  broad  stigmas  of  three  of  them 
were  perfectly  free  from  pollen,  but  a  little  had  fallen 
on  one  corner  of  the  fourth.     AVith  the  exception  of 


8-4  iLEETHUSE^.  Chap.  III. 

the  summit  of  one  pillar  in  this  latter  flower,  all  the 
other  pillars  still  stood  upright  and  unbroken.  I  looked 
at  the  flowers  of  some  surrounding  plants,  and  every- 
where found,  as  I  had  so  often  done  before,  broken-down 
pillars  and  masses  of  pollen  on  the  stigmas. 

From  the  usual  state  of  the  pillars  of  pollen,  as 
well  as  from  the  gnawed  condition  of  the  ridges  on  the 
labellum,  it  may  be  safely  inferred  that  insects  of  some 
kind  visit  the  flowers,  disturb  the  pollen,  and  leave 
masses  of  it  on  the  stigmas.  We  thus  see  that  the 
turning  down  of  the  distal  portion  of  the  labellum,  by 
which  a  temporary  landing-place  and  an  open  door  are 
afforded,— the  upturned  labellum,  by  which  the  flower 
is  made  tubular  so  that  insects  are  compelled  to  crawl 
close  by  the  stigmatic  surface, — the  pollen  readily 
cohering  to  any  object,  and  standing  in  friable  pillars 
protected  from  the  wind, — and,  lastly,  the  large  masses 
of  pollen  above  and  below  that  layer  of  grains,  the 
tubes  of  which  alone  penetrate  the  edge  of  the  stigma, — 
are  all  co-ordinated  structures,  far  from  useless ;  and 
they  would  be  quite  useless  if  these  flowers  were  always 
self- fertilised. 

To  ascertain  how  far  the  early  penetration  of  the 
upper  edge  of  the  stigma  by  the  tubes  of  those  grains 
which  rest  on  it,  is  effectual  for  fertilisation,  I  covered 
up  a  plant,  just  before  the  flowers  opened,  and  removed 
the  thin  net  as  soon  as  they  had  begun  to  wither.  From 
long  experience  I  am  sure  that  this  temporary  cover- 
ing could  not  have  injured  their  fertility.  The  four 
covered  flowers  produced  seed-capsules  as  fine  in  ap- 
pearance as  those  on  any  of  the  surrounding  plants. 
When  ripe,  I  gathered  them,  and  likewise  capsules 
from  several  of  the  surrounding  plants,  growing  under 
similar  conditions,  and  weighed  the  seed  in  a  chemical 
balance.     The  seeds  from   the  four   capsules  on   the 


Chap.  IIP.         CEPHALANTHERA   GRANDIFLORA.  85 

uncovered  plants  weighed  1  •  5  grain ;  whilst  those 
from  an  equal  number  of  capsules  on  the  covered  plant 
weighed  under  1  grain ;  but  this  does  not  give  a  fair 
idea  of  the  relative  difference  of  their  fertility,  for  I 
observed  that  a  great  number  of  the  seeds  from  the 
covered  plant  consisted  of  minute  and  shrivelled  husks. 
Accordingly  I  mixed  the  seeds  well  together,  and  took 
four  little  lots  from  one  heap  and  four  little  lots  from 
the  other  heap,  and,  having  soaked  them  in  water,  com- 
pared them  under  the  microscope  :  out  of  forty  seeds 
from  the  uncovered  plants  there  were  only  four  bad 
ones,  whereas  out  of  forty  seeds  from  the  covered-up 
plants  there  were  at  least  twenty-seven  bad ;  so  that 
there  were  nearly  seven  times  as  many  bad  seeds  from 
the  covered  plants,  as  from  those  left  free  to  the  access 
of  insects. 

We  may  therefore  cor- elude  that  this  orchid  is 
constantly  self-fertilised,  although  in  a  very  imperfect 
manner ;  but  this  would  be  highly  useful  to  the  plant, 
if  insects  failed  to  visit  the  flowers.  The  penetra- 
tion of  the  pollen-tubes,  however,  is  apparently  even 
more  serviceable  by  retaining  the  pillars  of  pollen  in 
their  proper  places,  so  that  insects,  in  crawling  into  the 
flowers,  may  get  dusted  with  pollen.  Self-fertilisation 
also  may,  perhaps,  be  aided  by  insects,  carrying  pollen 
from  the  same  flower  on  to  the  stigma ;  but  an  insect 
thus  smeared  with  pollen  could  hardly  fail  likewise  to 
cross  the  flowers  on  other  plants.  From  the  relative 
position  of  the  parts,  it  seems  indeed  probable  (but  I 
omitted  to  prove  this  by  the  early  removal  of  the 
anthers,  so  as  to  observe  whether  pollen  was  brought 
to  the  stigma  from  other  flowers)  that  an  insect  would 
more  frequently  get  dusted  by  crawling  out  of  a  flower 
than  by  crawling  into  one  ;  and  this  would  of  course 
facilitate  a  cross  between  distinct  individuals.     Hence 


86  ARETHUSE.E.  Chap.  III. 

Cephalanthera  offers  only  a  partial  exception  to  the 
rule  that  the  flowers  of  Orchids  are  generally  fertilised 
by  pollen  from  another  plant. 

Cephalanthera  ensifolia. — According  to  Delpino,*  the 
flowers  of  this  species  are  visited  by  insects,  as  shown 
by  the  removal  of  the  pollen-masses.  He  believes  that 
this  is  effected  by  their  bodies  being  first  rendered  sticky 
by  means  of  the  stigmatic  secretion.  It  is  not  clear 
whether  the  flowers  also  fertilise  themselves.  Each 
pollen-mass  is  divided  into  two,  instead  of  being  merely 
sub-divided,  so  that  there  are  four  distinct  pollen-masses. 

Pogonia  ophioglossoides. — The  flowers  of  this  plant, 
an  inhabitant  of  the  United  States,  resemble,  as 
described  by  Mr.  Scudder,  f  those  of  Cephalanthera  in 
not  having  a  rostellum,  and  in  the  pollen-masses  not 
being  furnished  with  caudicles.  The  pollen  consists  of 
powdery  grains  not  united  by  threads.  Self-fertilisation 
seems  to  be  effectually  prevented ;  and  the  flowers  on 
distinct  plants  must  intercross,  for  each  plant  generally 
bears  only  a  single  flower. 

Fterostylis  trullifolia  and  lo7igifolia. — I  may  here 
briefly  mention  some  Orchids,  inhabitants  of  Australia 
and  New  Zealand,  which  are  included  by  Lindley  in 
the  same  family  of  the  Arethusese  with  Cephalanthera 
and  Pogonia,  and  are  remarkable  from  their  labella 
being  extremely  sensitive  or  irritable.  Two  of  the 
petals  and  one  of  the  sepals  form  a  hood  which  encloses 
the  column,  as  may  be  seen  at  A  in  the  accompanying 
figure  of  Fterostylis  longifolia. 

The  distal  portion  of  the  labellum  affords  a  landing- 
place  for  insects,  in  nearly  the  same  manner  as  with 
Cephalanthera;  but  when  this  organ  is  touched  it 
rapidly  springs  up,  carrying  with  it  the  touching  insect, 

*  •  Ult.   Osservaz.    sulla    Dico-  f  '  Proe.  Boston  Soc.  Nat.  Hi&t.* 

gamia,'  pail  ii.  1875,  p.  149.  vol.  ix.  1863,  p.  182. 


Chap.  III. 


PTEEOSTYLIS   LONGIFOLIA. 


87 


which  is  thus  temporarily  imprisoned  within  the  other- 
wise almost  completely  closed  flower.     The  labellum 


Fi2.  14. 


Pterostylis  longifoLia.  (Copied  from  Mr.  R.  D.  Fitzgerald's  *  Australian 
Orchids.') 


A.  Flower  in  its  natural  state:  the 

outline  of  the  column  is  dimly- 
seen  within. 

B.  Flower    with    the    near    lateral 

petal    removed,    showing    the 


column  with  its  two  shields, 
and  the  labellum  in  the  position 
which  it  occupies  after  having 
been  touched 


remains  shut  from  half  an  hour  to  one  hour  and  a 
half,  and  on  reopening  is  again  sensitive  to  a  touch. 
Two  membranous  shields  project  on  each  side  of  the 


88  AKETIIUSEJE.  Chap.  HI. 

upper  part  of  the  column,  with  their  edges  meeting 
in  front,  as  may  be  seen  in  fig.  B.  In  this  drawing 
the  petal  on  the  near  side  has  been  cut  away,  and 
the  labellum  is  represented  in  the  position  which  it 
assumes  after  having  been  touched.  As  soon  as  the 
labellum  has  thus  risen,  an  imprisoned  insect  cannot 
escape  except  by  crawling  through  the  narrow  passage 
formed  by  the  two  projecting  shields.  In  thus  escaping 
it  can  hardly  fail  to  remove  the  poUinia,  as,  before 
coming  into  contact  with  them,  its  body  will  have  been 
smeared  with  the  viscid  matter  of  the  rostellum.  On 
being  imprisoned  in  another  flower,  and  on  again  escap- 
ing by  the  same  passage,  it  will  almost  certainly  leave 
at  least  one  of  the  four  pollen-masses  on  the  adhesive 
stigma,  and  thus  fertilise  the  flower. 

All  that  I  have  here  said  is  taken  from  the  admir- 
able description  given  by  Mr.  Cheeseman  *  of  Pterostylis 
trullifolia  ;  but  I  have  copied  the  figure  of  P.  longifolia 
from  Mr.  Fitzgerald's  great  work  on  the  Australian 
Orchids,  as  it  shows  plainly  the  relation  of  all  the  parts. 

Mr.  Cheeseman  placed  insects  within  several  flowers 
of  P.  truUifolia,  and  saw  them  afterwards  crawl  out, 
generally  with  pollinia  attached  to  their  backs.  He 
also  proved  the  importance  of  the  irritable  labellum 
by  removing  it  from  twelve  flowers  whilst  yonng,  and 
in  this  case  insects  which  entered  the  flowers  would  not 
have  been  compelled  to  crawl  out  through  the  passage ; 
and  not  one  of  these  flowers  produced  a  capsule.  The 
flowers  seem  to  be  frequented  exclusively  by  Diptera ; 
but  what  attraction  they  present  is  not  known,  as  they 
do  not  secrete  nectar.  Mr.  Cheeseman  believes  that 
hardly  a  quarter  of  the  flowers  prod\ice  capsules  ;  not- 
withstanding that  on  one  occasion  he  examined  110 

♦  *  Transact.  New  Zealand  Institute,'  vol.  v.  IS73,  p  352 ;  and  vol. 
fii.  p.  351. 


CuAP.  III.  PTEROSTYLIS   LONGIFOLIA.  89 

flowers  in  a  withered  condition,  and  seventy-one  of  these 
had  pollen  on  their  stigmas,  and  only  twenty-eight  had 
all  four  pollinia  still  within  their  anthers.  All  the 
New  Zealand  species  bear  solitary  flowers,  so  that  dis- 
tinct plants  cannot  fail  to  be  intercrossed.  I  may  add 
that  Mr.  Fitzgerald  also  placed  a  small  beetle  on  the 
labellum  of  P.  longifolia^  which  was  instantly  carried 
into  the  flower  and  imprisoned ;  afterwards  he  saw 
it  crawl  out  with  two  pollinia  attached  to  its  back. 
Nevertheless  he  doubts,  from  reasons  which  seem  to 
me  quite  insufficient,  whether  the  sensitiveness  of  the 
labellum  is  not  as  great  a  disadvantage  as  an  advan- 
tage to  the  plant. 

Mr.  Fitzgerald  has  described  another  Orchid  belong- 
ing to  the  same  sub-tribe,  Ccdadenia  dimorpha,  which 
has  an  irritable  labellum.  He  kept  a  plant  in  his  room, 
and  says  :  "  A  house-fly  lighting  on  the  lip  was  carried 
by  its  spring  against  the  column,  and  becoming  en- 
tangled in  the  gluten  of  the  stigma,  and  struggling  to 
escape,  removed  the  pollen  from  the  anther  and  smeared 
it  on  the  stigma."  He  adds,  "  Without  some  such  aid 
the  species  of  this  genus  never  produce  seed."  But 
from  the  analogy  of  other  Orchids  we  may  feel  sure 
that  insects  usually  behave  very  differently  from  the 
fly  which  he  saw  caught  on  the  stigma,  and  no  doubt 
they  carry  the  pollen-masses  from  plant  to  plant.  The 
labellum  of  another  Australian  genus,  Calrena,  one  oi 
the  Arethusese,  is  said  by  Dr.  Hooker  *  to  be  irritable  ; 
so  that  when  touched  by  an  insect  it  shuts  up  suddenly 
against  the  column,  and  temporarily  encloses  its  prey 
as  it  were  within  a  box.  The  labellum  is  covered  by 
curious  papillae,  which,  as  far  as  Mr.  Fitzgerald  has 
seen,  are  not  gnawed  by  insects. 


Flora  of  Tasmatiia,*  vol.  ii.  p.  17. 


90  AKETHUSE^.  Chap.  Ill 

Mr.  Fitzgerald  describes  and  figures  several  other 
genera,  and  states  with  respect  to  Acianthus  fornicatus 
and  exsertus  that  neither  species  produce  seeds  if 
protected  from  insects,  but  are  easily  fertilised  by 
pollen  placed  on  their  stigmas.  Mr.  Cheeseman  *  has 
witnessed  the  fertilisation  of  Acianthus  sinclairii  in 
New  Zealand,  the  flowers  of  which  are  incessantly 
visited  by  Diptera,  without  whose  aid  the  pollinia  are 
never  removed.  Out  of  eighty-seven  flowers  borne 
by  fourteen  plants,  no  less  than  seventy-one  matured 
capsules.  This  plant  according  to  the  same  observer 
exhibits  one  remarkable  peculiarity,  namely,  that  the 
pollen-masses  are  attached  to  the  rostellum  by  means 
of  the  exserted  pollen-tubes,  which  serve  as  a  caudicle ; 
and  the  pollen-masses  are  thus  removed  together  with 
the  rostellum,  which  is  viscid,  when  the  flowers  are 
visited  by  insects.  The  flowers  of  the  allied  Cyrto- 
stylis  are  also  much  frequented  by  insects,  but  the 
pollinia  are  not  so  regularly  removed  as  those  of  the 
Acianthus ;  and  with  Corysanthes,  only  five  out  of  200 
flowers  produced  capsules. 

The  Vanillidse  according  to  Lindley  form  a  sub- 
tribe  of  the  Arethusese.  The  large  tubular  flowers  of 
Vanilla  aromatica  are  manifestly  adapted  to  be  ferti- 
lised by  insects ;  and  it  is  known  that  when  this  plant 
is  cultivated  in  foreign  countries,  for  instance  in  Bour- 
bon, Tahiti,  and  the  East  Indies,  it  fails  to  produce 
its  aromatic  pods  unless  artificially  fertilised.  This 
fact  shows  that  some  insect  in  its  American  home  is 
specially  adapted  for  the  work ;  and  that  the  insects 
of  the  above-named  tropical  regions,  where  the  Yanilla 
flourishes,  either  do  not  visit  the  flowers,  though  they 
secrete  an  abundance  of  nectar,  or  do  not  visit  them 


*  '  Transact.  New  Zealand  Institute,*  vol.  vii.  1875,  p.  843. 


Chap.  III.  PTEROSTYLIS   LONGIFOLIA.  91 

in  the  proper  manner.*  I  will  mention  only  two  pecu- 
liarities in  the  structure  of  the  flowers :  the  anterior 
part  of  the  pollen-masses  is  semi-waxy  and  the  posterior 
part  somewhat  friable ;  the  grains  are  not  cemented 
together  into  compound  grains,  and  the  single  grains 
are  not  united  by  fine  elastic  threads  but  by  viscid 
matter;  this  matter  would  aid  in  causing  the  pollen 
to  adhere  to  an  insect,  but  I  should  have  thought  that 
such  aid  was  superfluous,  as  the  viscid  rostellum  is 
well  developed.  The  other  peculiarity  is  that  the 
labellum,  in  front  of  the  stigma,  and  some  way  beneath 
it,  is  furnished  with  a  stiff  hinged  brush,  formed  of  a 
series  of  combs  one  over  the  other,  which  point  down- 
wards. This  structure  would  allow  an  insect  to  crawl 
easily  into  a  flower,  but  would  compel  it  whilst  re- 
treating to  press  close  against  the  column ;  and  in 
doing  so  it  would  remove  the  pollen-masses,  leaving 
them  on  the  stigma  of  the  next  flower  which  was 
visited. 

The  genus  Sobralia  is  allied  to  Vanilla,  and  Mr. 
Cavendish  Browne  informs  me  that  he  saw  a  large 
humble-bee  enter  a  flower  of  S.  macrantha  in  his 
hothouse,  and  when  it  crawled  out  it  had  the  two 
large  pollen- masses  firmly  fixed  to  its  back,  nearer  to 
the  tail  than  to  the  head.  The  bee  then  looked  about, 
and  seeing  no  other  flower  re-entered  the  same  one  of 


*  For  Bmibon  see  'Bui.  Soc.  in  the  Blue  Mountains  of  New 
Bot.  de  France,' torn.  i.  18f»4.  p.  South  Wiiles;  removed  from 
290.  For  Tahiti  see  H.  A.  Tilley,  theiiee  to  Sydney,  a  number  of 
'Japan,  the  Amour,  &o./  1861,  p.  plants,  though  {iowerinj?  well,  have 
375.  For  the  East  Indies  tee  not  borne  any  seed  if  left  to  them- 
Morren  in  'Annals  and  Mag.  of  selves,  though  invariably  fertile 
Nat.  Hist.'  1839,  vol.  iii.  p.  6.  I  when  the  pollen-masses  were  re- 
may  give  an  analogous  but  more  moved  and  placed  on  the  stigma." 
striking  case  from  Mr  Fitzgerald,  Yet  the  Blue  Mountains  are  less 
who  says  "that  Sarcochilus  par-  than  one  hundred  miles  dibtaiit 
vijlorus  (one  of  the  Vandeae)  pro-  fiom  Sydney, 
duces  capsules   not  unfrequently 


92  AEETHUSE^.  CflAP.  III. 

the  Sobralia,  but  quickly  retreated,  leaving  the  pollen- 
masses  on  the  stigma,  with  the  viscid  discs  alone 
adhering  to  its  back.  The  nectar  of  this  Guatemala 
Orchid  seemed  too  powerful  for  our  British  bee,  for  it 
stretched  out  its  legs  and  lay  for  a  time  as  if  dead  on 
the  labellum,  but  afterwards  recovered. 


Chap.  IV.  EPIPACTIS  PALUSTEIS.  93 


CHAPTER  IV. 

NEOTTE^. 

Epipactis  palustris ;  curious  shape  of  the  labellura  and  its  importance 
ill  the  fructification  of  the  flower— Other  species  of  Epipactis — 
Epipogiiira  —  Goodyera  repens  —  Sjuranthes  autumnalis;  perfect 
adapt  ition  by  which  the  pollen  of  a  younger  flower  is  carried  to  the 
stigma  of  an  older  flower  on  another  plant— Listera  ovata ;  sensi- 
tiveness of  the  rostellum;  explosion  of  viscid  matter;  action  of 
insects ;  perfect  adaptation  of  the  several  organs — Listera  cordata — 
Ncottia  nidus-avis ;  its  fertilisation  efiected  in  the  same  manner  as 
in  Listera — Thelymitra,  self-fertile. 

We  have  now  arrived  at  a  third  tribe,  the  Neottene  of 
Lindley,  which  includes  several  British  genera.  These 
present  many  interesting  points  with  respect  to  their 
strncture  and  manner  of  fertilisation. 

The  Neottese  have  a  free  anther  standing  behind  the 
stigma.  Their  pollen-grains  are  tied  together  by  fine 
elastic  threads,  which  partially  cohere  and  project  at 
the  upper  end  of  the  pollen-mass,  being  there  attached 
(with  some  exceptions)  to  the  back  of  the  rostellum. 
Consequently  the  pollen-masses  have  no  true  and  dis- 
tinct caudicles.  In  one  genus  alone  (Goodyera)  the 
pollen-grains  are  collected  into  packets  as  in  Orchis. 
Epipactis  and  Goodyera  agree  pretty  closely  in  their 
manner  of  fertilisation  with  the  Ophreae,  but  are  more 
simply  organised.  Spiranthes  comes  under  the  same 
category,  but  has  been  differently  modified  in  some 
respects. 

Epipactis  palustris* — The  lower  part  of  the  large 


*  I  am  much  indebted  to  INIr.       ing  me   frosh   specimens  of  thi 
A.  G.  ]Mnre,  of  Bembridge.  in  the       beautiful  Orchis. 
I>le  of  Wight,  for  repeatedly  send- 


94 


Chap.  IV. 


EpIPACI'IS   PALUSTRI8. 


a.  anther,  with  the  two  open  cells 
seen  in  the  front  view  D. 

a',  rudin.entary  anther,  or  auricle, 
referred  to  in  a  future  chapter. 

r.    rostellum. 

s.    stigma. 

l.     labellum. 

A.  Side  view  of  flower,  with    the 

lower  sepals  removed,  in  its 
natural  position. 

B.  Side  view   of  flower,  with  the 

distal  portion  of  the  labellum 
depressed,  as  if  by  the  weight 
of  an  insect. 

C.  Side    view  c  f  flower,  somewhat 


enlarged,  with  all  the  sepals 
and  petals  removed,  excepting 
the  labellum,  of  which  the 
near  side  has  been  cut  away ; 
the  massive  anther  is  seen  to 
be  of  large  size. 
D.  Front  view  of  column,  somewhat 
enlarged,  with  all  the  sepals 
and  petals  removed:  the  ros- 
tellum has  sunk  down  a  little 
in  the  specimen  figured,  and 
ought  to  have  stood  higher, 
so  as  to  hide  more  of  the 
anther-cells. 


Chap.  IV.  EPIPACTIS  PALUSTRIS.  95 

stigma  is  bilobed  and  projects  in  front  of  the  column 
(see  s  in  the  side  and  front  views,  C,  J),  fig.  15).  On 
its  square  summit  a  single,  nearly  globular  rostellum 
is  seated.  The  anterior  face  of  the  rostellum  (r,  C,  D) 
projects  a  little  beyond  the  surface  of  the  upper  part  of 
the  stigma,  and  this  is  of  importance.  In  the  early  bud 
the  rostellum  consists  of  a  friable  mass  of  cells,  with  the 
exterior  surface  rough  :  these  superficial  cells  undergo 
a  great  change  during  development,  and  become  con- 
verted into  a  soft,  smooth,  highly  elastic  membrane  or 
tissue,  so  excessively  tender  that  it  can  be  penetrated 
by  a  human  hair;  when  thus  penetrated,  or  when 
slightly  rubbed,  the  surface  becomes  milky  and  in  some 
degree  viscid,  so  that  the  pollen-grains  adhere  to  it. 
In  some  cases,  though  I  observed  this  more  plainly  in 
E]pi][)aGtis  latifolia,  the  surface  of  the  rostellum  appa- 
rently becomes  milky  and  viscid  without  having  been 
touched.  This  exterior  soft  elastic  membrane  forms 
a  cap  to  the  rostellum,  and  is  internally  lined  with  a 
layer  of  much  more  adhesive  matter,  which,  when  ex- 
posed to  the  air,  dries  in  from  five  to  ten  minutes. 
By  a  slight  upward  and  backward  push  with  any  object, 
the  whole  cap,  with  its  viscid  lining,  is  removed  with 
the  greatest  ease ;  a  minute  square  stump,  the  basis 
of  the  rostellum,  being  alone  left  on  the  summit  of  the 
stigma. 

In  the  bud-state  the  anther  stands  quite  free  behind 
the  rostellum  and  stigma;  it  opens  longitudinally 
whilst  the  flower  is  still  unexpanded,  and  exposes  the 
two  oval  pollen-masses,  which  now  lie  loose  in  their 
cells.  The  pollen  consists  of  spherical  granules,  co- 
hering in  fours,  but  not  affecting  each  other's  shapes : 
and  these  compound  grains  are  tied  together  by  fine 
elastic  threads.  The  threads  are  collected  into  bundles 
extending  longitudinally  along  the  middle  line  of  the 


96  NEOTTE.E.  Chap.  IV 

front  of  each  pollinium,  where  it  comes  into  contact 
with  the  back  of  tne  uppermost  part  of  the  rostellum. 
From  the  number  of  these  threads  this  middle  line 
looks  browTi,  and  each  pollen-mass  here  shows  a 
tendency  to  divide  longitudinally  into  halves.  In  all 
these  respects  there  is  a  close  general  resemblance  to 
the  poUinia  of  the  Ophrese. 

The  line  where  the  parallel  threads  are  the  most 
numerous  is  the  line  of  greatest  strength ;  elsewhere 
the  pollen-masses  are  extremely  friable,  so  that  large 
portions  can  easily  be  broken  off.  In  the  bud-state 
the  rostellum  is  curved  a  little  backwards,  and  is 
pressed  against  the  recently-opened  anther ;  and  the 
above-mentioned  slightly  projecting  bundles  of  threads 
become  firmly  attached  to  the  posterior  flap  of  the 
membranous  cap  of  the  rostellum.  The  point  of  attach- 
ment lies  a  little  beneath  the  summit  of  the  pollen- 
masses  ;  but  the  exact  point  is  somewhat  variable,  for 
I  have  met  with  specimens  in  which  the  attachment 
was  one-fifth  of  the  length  of  the  pollen-masses  from 
their  summits.  This  variability  is  so  far  interesting, 
as  it  is  a  step  leading  to  the  structure  of  the  Ophrese, 
in  which  the  confluent  threads,  or  caudicles,  always 
spring  from  the  lower  ends  of  the  pollen-masses.  After 
the  pollinia  are  firmly  attached  by  their  threads  to 
the  back  of  the  rostellum,  the  rostellum  bends  a  little 
forwards,  and  this  partly  draws  the  pollinia  out  of  the 
anther-cells.  The  upper  end  of  the  anther  consists  of  a 
blunt,  solid  point,  not  including  pollen ;  this  blunt  point 
projects  slightly  beyond  the  face  of  the  rostellum, 
which  circumstance,  as  we  shall  see,  is  important. 

The  flowers  stand  out  (fig.  A)  almost  horiozontally 
from  the  stem.  The  labellum  is  curiously  shaped,  as 
may  be  seen  in  the  drawings :  the  distal  half,  which 
projects  beyond  the  other  petals  and  forms  an  excellent 


Chai'.  IV.  EPIPACTIS   PALUSTPvIS.  97 

landing-place  for  insects,  is  joined  to  the  basal  half  by 
a  narrow  hinge,  and  naturally  (fig.  A)  is  turned  a  little 
upwards,  so  that  its  edges  pass  within  the  edges  of  the 
basal  portion.  So  flexible  and  elastic  is  the  hinge  that 
the  weight  of  even  a  fly,  as  Mr.  More  informs  me, 
depresses  the  distal  portion  ;  it  is  represented  in  fig.  B 
in  this  state ;  but  when  the  weight  is  removed  it 
instantly  springs  up  to  its  former  position  (fig.  A),  and 
with  its  curious  medial  ridges  partly  closes  the  entrance 
into  the  flower.  The  basal  portion  of  the  labellum  forms 
a  cup,  which  at  the  proper  time  is  filled  with  nectar. 

Now  let  us  see  how  all  the  parts,  which  I  have  been 
obliged  to  describe  in  detail,  act.  When  I  first  ex- 
amined these  flowers  I  was  much  perplexed :  trying  in 
the  same  manner  as  I  should  have  done  with  a  true 
Orchis,  I  slightly  pushed  the  protuberant  rostellum 
downwards,  and  it  was  easily  ruptured  ;  some  of  the 
viscid  matter  was  withdrawn,  but  the  pollinia  remained 
in  their  cells.  Reflecting  on  the  structure  of  the 
flower,  it  occurred  to  me  that  an  insect  in  entering  one 
in  order  to  suck  the  nectar,  would  depress  the  distal 
portion  of  the  labellum,  and  consequently  would  not 
touch  the  rostellum  ;  but  that,  when  within  the  flower, 
it  would  be  almost  compelled,  from  the  springing  up 
of  this  distal  half  of  the  labellum,  to  rise  a  little  up- 
wards and  back  out  parallel  to  the  stigma.  I  then 
brushed  the  rostellum  lightly  upwards  and  backwards 
with  the  end  of  a  feather  and  other  such  objects  ;  and 
it  was  pretty  to  see  how  easily  the  membranous  cap 
of  the  rostellum  came  off,  and  how  well  from  its  elas- 
ticity it  fitted  any  object,  whatever  its  shape  might  be, 
and  how  firmly  it  clung  to  the  object  owing  to  the 
viscidity  of  its  under  surface.  Large  masses  of  pollen, 
adhering  by  the  elastic  threads  to  the  cap  of  the  ros- 
tellum were  at  the  same  time  withdrawn. 


98  NEOTTE.E.  CiiAK  IV. 

Nevertheless  the  pollen-masses  were  not  removed 
nearly  so  cleanly  as  those  which  had  been  naturally 
removed  by  insects.  I  tried  dozens  of  flowers,  always 
with  the  same  imperfect  result.  It  then  occurred  to 
me,  tliat  an  insect  in  backing  out  of  the  flower  would 
naturally  push  with  some  part  of  its  body  against  the 
blunt  and  projecting  upper  end  of  the  anther,  which 
overhangs  the  stigmatic  surface.  Accordingly  I  so 
held  a  brush  that,  whilst  brushing  upwards  against  the 
rostellum,  I  pushed  against  the  blunt  solid  end  of  the 
anther  (see  flg.  C) ;  this  at  once  eased  the  pollinia,  and 
they  were  withdrawn  in  an  entire  state.  At  last  I 
understood  the  mechanism  of  the  flower. 

The  large  anther  stands  above  and  behind  the 
stigma,  forming  an  angle  with  it  (fig.  C),  so  that  the 
pollinia  when  withdrawn  by  an  insect  would  adhere 
to  its  head  or  body  in  a  position  fitted  to  strike  the 
sloping  stigmatic  surface  as  soon  as  another  flower 
was  visited.  Hence  we  have  not  here,  or  in  any  of 
the  Neottese,  that  movement  of  depression  so  common 
with  the  pollinia  of  the  Ophreae.  When  an  insect 
with  the  pollinia  attached  to  its  back  or  head  enters 
another  flower,  the  easy  depression  of  the  distal  portion 
of  the  labellum  probably  plays  an  important  part ;  for 
the  pollen-masses  are  extremely  friable,  and  if  they 
were  struck  against  the  tips  of  the  petals  much  of  the 
pollen  would  be  lost ;  but  as  it  is,  an  open  gangway 
is  offered,  and  the  viscid  stigma,  with  its  lower  pro- 
tuberant part  lying  in  front,  is  the  first  object  against 
which  the  pollen -masses  projecting  forwards  from  the 
insect's  head  or  back  would  naturally  strike.  I  may 
add  that  in  one  large  lot  of  flower-spikes,  a  great 
majority  of  the  pollinia  had  been  naturally  and 
cleanly  removed. 

In  order  to  ascertain  m  hether  I  was  right  in  believing 


Chap.  IV.  EPIPACTIS   rALUSTlUS.  99 

tliat  the  distal  hinged  portion  of  the  labellum  was  of 
importance  in  the  fertilisation  of  the  flowers,  I  asked 
Mr.  More  to  remove  this  part  from  some  young  flowers, 
and  to  mark  them.  He  tried  the  experiment  on  eleven 
flowers,  three  of  which  did  not  produce  seed-capsules; 
but  this  may  have  been  accidental.  Of  the  eight 
capsules  which  were  produced,  two  contained  about  as 
many  seeds  as  those  from  unmutilated  flowers  on  the 
same  plant ;  but  six  capsules  contained  much  fewer 
seeds.  Most  of  the  seeds  were  well-formed.  These 
experiments,  as  far  as  they  go,  support  the  view  that 
the  distal  part  of  the  labellum  is  of  importance  in 
causing  insects  to  enter  and  leave  the  flowers  in  the 
best  manner  for  their  fertilisation. 

Since  the  appearance  of  the  first  edition  of  this  book, 
my  son  William  has  observed  for  me  this  Epipactis  in 
the  Isle  of  Wight.  Hive-bees  seem  to  be  the  chief 
agents  in  fertilisation ;  for  he  saw  them  visit  about  a 
score  of  flowers,  and  many  had  pollen-masses  attached 
to  their  foreheads,  just  above  the  mandibles.  I  had 
supposed  that  insects  always  crawled  into  the  flowers  ; 
but  hive-bees  are  too  large  to  do  this;  they  always 
clung,  whilst  sucking  the  nectar,  to  the  distal  and 
hinged  half  of  the  labellum,  which  was  thus  pressed 
downwards.  Owing  to  this  part  being  elastic  and 
tending  to  spring  up,  the  bees,  as  they  left  the  flowers, 
seemed  to  fly  rather  upwards ;  and  this  favoured,  in 
the  manner  previously  explained,  the  complete  with- 
drawal of  the  pollen-masses,  quite  as  well  as  if  the 
insects  had  crawled,  in  an  upward  direction,  out  of 
the  flower.  Perhaps  the  upward  movement  may  not 
be  so  necessary  in  all  cases  as  I  had  supposed ;  for, 
judging  from  the  manner  in  which  the  pollen-masses 
were  attached  to  the  hive-bees,  the  back  part  of  their 
heads  could  hardly  fail  to  press  against  and  lift  up  the 


LOO  NEOTTEiE.  Chap.  IV. 

blunt,  solid,  upper  end  of  the  anther,  thus  freeing  the 
pollen-masses.  Various  other  insects  besides  hive-bees 
visit  the  flowers.  My  son  saw  several  large  flies  (Sar- 
cophaga  carnosa)  haunting  them;  but  they  did  not 
enter  in  so  neat  and  regular  a  manner  as  the  hive-bees  ; 
nevertheless  two  had  pollen-masses  attached  to  their 
foreheads.  Several  smaller  flies  (Coelojja  frigida)  were 
also  seen  entering  and  leaving  the  flowers,  with  pollen- 
masses  adhering  rather  irregularly  to  the  dorsal  surface 
of  the  thorax.  Three  or  four  distinct  kinds  of  Hymen- 
optera  (one  of  small  size  being  Crabro  hrevis)  likewise 
visited  the  flowers ;  and  three  of  these  Hymenoptera 
had  pollen-masses  attached  to  their  backs.  Other  still 
more  minute  Diptera,  Coleoptera,  and  ants  w^ere  seen 
sucking  the  nectar ;  but  these  insects  appeared  to  be 
too  small  to  transport  the  pollen-masses.  It  is  re- 
markable that  some  of  the  foregoing  insects  should 
visit  the  flowers ;  for  Mr.  F.  Walker  informs  me  that 
the  Sarcophaga  frequents  decaying  animal  matter,  and 
the  Ccelopa  haunts  seaweed,  occasionally  settling  on 
flowers.  The  Crabro  also,  as  I  hear  from  Mr.  F.  Smith, 
collects  small  beetles  (Halticae)  for  provisioning  its 
nest.  It  is  equally  remarkable,  seeing  how  many 
kinds  of  insects  visit  this  Epipactis,  that  although  my 
son  watched  hundreds  of  plants  for  some  hours  on  three 
occasions,  not  a  single  humble-bee  alighted  on  a  flower, 
though  many  were  flying  about. 

Epipactis  latifolia,  —  This  species  agrees  with  the 
last  in  most  respects.  The  rostellum,  however,  projects 
considerably  further  beyond  the  face  of  the  stigma, 
and  the  blunt  upper  end  of  the  anther  less  so.  The 
viscid  matter  lining  the  elastic  cap  of  the  rostellum 
takes  a  longer  time  to  get  dry.  The  upper  petals  and 
sepals  are  more  widely  expanded  than  in  E.  palustris : 
the  distal  portion  of  the  labellum  is  smaller,  and  is 


Chap.  IV.  EPIPACTIS    LATIFOLIA.  101 

firmly  united  to  the  basal  portion  (fig.  16),  so  that  it 
is  not  flexible  and  elastic ;  it  apparently  serves  only  as 
a  landing-place  for  insects.  The  fertilisation  of  this 
species  depends  simply  on  an  insect  striking  in-  an 
upward  and  backward  direction  the  highly-protuberant 
rostellum,  which  it  would  be  apt  to  do  when  retreating 
from  the  flower  after  having  sucked  the  copious  nectar 

Fi?.  16. 


EpIPACTIS  LATIFOLIA. 

Flower  viewed  sideways,  with  all  the  sepals  and  petals  removed,  except  the 
label  lum. 

a.  anther.  I  s.    stigma. 

r.   rostellum.  '  /.    labellum. 

in  the  cup  of  the  labellum.  Apparently  it  is  not  at 
all  necessary  that  the  insect  should  push  upwards  the 
blunt  upper  end  of  the  anther ;  at  least  I  found  that 
the  pollinia  could  be  removed  easily  by  simply  drag- 
ging off  the  cap  of  the  rostellum  in  an  upward  or 
backward  direction. 

As  some  plants  grew  close  to  my  house,  I  have  been 
able  to  observe  here  and  elsewhere  their  manner  of 
fertilisation  during  several  years.  Although  hive-bees 
and  humble-bees  of  many  kinds  were  constantly  flying 
over  the  plants,  I  never  saw  a  bee  or  any  Dipterous 
insect  visit  the  flowers ;  but  in  Germany  Sprengel 
caught  a  fly  with  the  pollinia  of  this  plant  attached 
to  its  back.     On  the  other  hand   I  have  repeatedly 


102  NEOTTEiE.  Chap.  IV. 

observed  the  common  wasp  (Vespa  si/Ivestris)  sucking 
the  nectar  out  of  the  open  cup-shaped  labellum.  I 
thus  saw  the  act  of  fertilisation  effected  by  the  pollen- 
masses  being  removed  by  the  wasps,  and  afterwards 
carried  attached  to  their  foreheads  to  other  flowers. 
Mv.  Oxenden  also  informs  me  that  a  large  bed  of 
E.  purpurafa  (which  is  considered  by  some  botanists  to 
be  a  distinct  species,  and  by  others  a  variety)  was  fre- 
quented by  "  swarms  of  wasps."  It  is  very  remarkable 
that  the  sweet  nectar  of  this  Epipactis  should  not  be 
attractive  to  any  kind  of  bee.  If  wasps  were  to  become 
extinct  in  any  district,  so  probably  would  the  Epipactis 
latifolia. 

To  show  how  effectually  the  flowers  are  fertilised,  I 
may  add  that  during  the  wet  and  cold  season  of  1860  a 
friend  in  Sussex  examined  five  spikes  bearing  eighty-five 
expanded  flowers  ;  of  these,  fifty-three  had  the  pollinia 
removed,  and  thirty-two  had  them  in  place  :  but  as 
many  of  the  latter  were  immediately  beneath  the  buds, 
a  larger  number  would  almost  certainly  have  been 
afterwards  remowed.  In  Devonshire  I  found  a  spike 
with  nine  open  flowers,  and  the  pollinia  in  all  were  re- 
moved with  one  exception,  and  in  this  case  a  fly,  too 
small  to  remove  the  pollinia,  had  become  glued  to  the 
rostellum,  and  had  there  miserably  perished. 

Dr.  H.  Miiller  has  published  *  some  interesting 
observations  on  the  difference  in  structure  and  manner 
of  fertilisation,  as  well  as  on  the  intermediate  forms 
between  Epipactis  ruhiginosa,  7iiiGrophyJla,  and  viridi- 
flora.  The  latter  species  is  remarkable  for  the  absence 
of  a  rostellum,  and  for  being  regularly  self-fertilised. 
Self-fertilisation  here  follows  from  the  incoherent 
pollen-grains   in  tlie  lower  part  of  the  pollen-masses 

*  •  Veiliandl.  d.  Nat.  Yer.  f.  W.  stfal.'  Ji.hig  xxv.  Ill  Folge,  v.Bd. 
pp.  7-3(5. 


Chap.  IV.  GOODYERA   REPENS.  103 

emitting,  whilst  still  within  the  anther-cells,  their 
tubes,  which  penetrate  the  stigma ;  and  this  occurs  even 
in  the  bud.  This  species,  however,  is  probably  visited 
by  insects,  and  occasionally  crossed  ;  for  the  labellum 
contains  nectar.  E.  microjphylla  is  intermediate  in 
structure  between  E.  latifoUa,  which  is  always  fertilised 
by  the  aid  of  insects,  and  E.  viridiflora,  which  does  not 
necessarily  require  any  such  aid.  The  whole  of  this 
memoir  by  Dr.  H.  Mtiller  deserves  to  be  attentively 
studied. 

Ejnpof/ium  gmelini. —  This  plant,  which  has  only 
once  been  found  in  Great  Britain,  has  been  fully  de- 
scribed by  Dr.  Eohrbach  in  a  special  memoir.  *  The 
structure  and  manner  of  fertilisation  is  in  many  re- 
spects like  that  of  Epipactis,  to  which  genus  the  author 
believes  the  present  one  to  be  allied,  though  placed  by 
Lindley  amongst  the  Arethusese.  Eohrbach  saw  the 
flowers  visited  by  Bomhus  lucorum,  but  it  appears  that 
only  a  few  produce  capsules. 

Goody  era  rejpens,^ — This  genus  is  rather  closely  re- 
lated to  Epipactis,  in  most  of  the  characters  with 
which  we  are  concerned.  The  shield-like  rostellum  is 
almost  square,  and  projects  beyond  the  stigma ;  it  is 
supported  on  each  side  by  sloping  sides  rising  from 
the  upper  edge  of  the  stigma,  in  nearly  the  same 
manner  as  we  shall  presently  see  in  Sj)iranthes.  The 
surface  of  the  protuberant  part  of  the  rostellum  is  rough, 
and  when  dry  can  be  seen  to  be  formed  of  cells  ;  it  is 
delicate,  and,  when  slightly  pricked,  a  little  milky 
viscid  fluid  exudes;  it  is  lined  by  a  layer  of  ver} 
adhesive  matter,  which  quickly  sets  hard  when  exposed 


•  'Ueber  den  Blutheiibau  von  f  Specimens  of  this  rare  High- 

Epipogium,'    &c.    186t);    see   also  land  Oicliid  were  kindly  sent  me 

Iriiiisfh,    'Beitrage    zur    liiologie  by  the  Kev.  G.  Gordon  uf  Elgin. 
der  Orehideen,'  1853,  p.  5o. 


]  04:  NEOTTE.E.  Chap.  IV. 

to  the  air.  The  protuberant  surface  of  the  rostelluin, 
when  gently  rubbed  upwards,  is  easily  removed,  and 
carries  with  it  a  strip  of  membrane,  to  the  hinder  part 
of  which  the  pollinia  are  attached.  The  sloping  sides 
which  support  the  rostellum  are  not  removed  at  the 
same  time,  but  remain  projecting  up  like  a  fork  and 
soon  wither.  The  anther  is  borne  on  a  broad  elon- 
gated filament ;  and  a  membrane  on  both  sides  unites 
this  filament  to  the  edges  of  the  stigma,  forming  an 
imperfect  cup  or  clinandrum.  The  anther-cells  open 
in  the  bud,  and  the  pollen-masses  become  attached 
by  their  anterior  faces,  just  beneath  their  summits, 
to  the  back  of  the  rostellum.  Ultimately  the  anther 
opens  widely,  leaving  the  pollinia  almost  naked,  but 
partially  protected  within  the  membranous  cup  or 
clinandrum.  Each  pollinium  is  partially  divided 
lengthways  ;  the  pollen-grains  cohere  in  subtriangular 
packets,  including  a  multitude  of  compound  grains,  each 
consisting  of  four  grains ;  and  these  packets  are  tied 
together  by  strong  elastic  threads,  which  at  their  upper 
ends  run  together  and  form  a  single  flattened  brown 
elastic  ribbon,  of  which  the  truncated  extremity  adheres 
to  the  back  of  the  rostellum. 

The  surface  of  the  orbicular  stigma  is  remarkably 
viscid,  which  is  necessary  in  order  that  the  unusually 
strong  threads  connecting  the  packets  of  pollen  should 
be  ruptured.  The  labellum  is  partially  divided  into 
two  portions  ;  the  terminal  portion  is  reflexed,  and 
the  basal  portion  is  cup-formed  and  filled  with  nectar. 
The  passage  between  the  rostellum  and  labellum  is 
contracted  whilst  the  flower  is  young ;  but  when  mature 
the  column  moves  further  back  from  the  labellum,  so 
as  to  allow  of  insects  with  the  pollinia  adhering  to 
their  proboscides,  to  enter  the  flowers  more  freely.  In 
many  of  the  specimens  received,  the  pollinia  had  been 


Chap.  IV.  GOODYEEA  REPENS.  105 

removed,  and  the  fork-shaped  supporting  sides  of  the 
rostellum  were  partially  withered.  Mr.  K.  B.  ThomsoQ 
inforDis  me  that  in  the  north  of  Scotland  he  saw  many 
humble-bees  (Bomhus  prat  or  urn)  visiting  the  flowers 
with  pollen-masses  attached  to  their  proboscides. 
This  species  grows  also  in  the  United  States;  and 
Professor  Asa  Gray*  confirms  my  account  of  its 
structure  and  manner  of  fertilisation,  which  is  likewise 
applicable  to  another  and  very  distinct  species,  namely, 
Goodijera  jpuhescens. 

Goodyera  is  an  interesting  connecting  link  between 
several  very  distinct  forms.  In  no  other  member  of 
the  iN'eotteae  observed  by  me  is  there  so  near  an  ap- 
proach to  the  formation  of  a  true  caudicle  ;  t  and  it  is 
curious  that  in  this  genus  alone  the  pollen-grains 
cohere  in  large  packets,  as  in  the  Ophreoe.  If  the 
nascent  caudicles  had  been  attached  to  the  lower  ends 
of  the  pollinia,  and  they  are  attached  a  little  beneath 
their  summits,  the  poUinia  would  have  been  almost 
identical  with  those  of  a  true  Orchis.  In  the  rostellum 
being  supported  by  sloping  sides,  which  wither  when 
the  viscid  disc  is  removed, — in  the  existence  of  a 
membranous  cup  or  clinandrum  between  the  stigma 

*  'Amer.  Journal   of  Science,*  bundle   of  elastic   threads,   witli 

vol.  xxxiv.  1862,  p.  427.     I  for-  very  small   and   thin  packets  of 

merly  thought  that  with  this  plant  pollen-grains   attached   to   them 

and  Spiranthes,  it  was  the  label-  and  arranged  like  tiles  one  over 

lum  which  moved  from  the  column  the  other.     The  two  caudieles  are 

to  allow  of  the  more  free  entrance  united  together  near  their  basos, 

of  insects  ;  but  Professor  Gray  is  where  they  are  attached  to  a  disc 

convinced  that  it  is  the  column  of    membrane    lined   with    viscid 

"which  moves.  matter.     From  the  small  size  and 

t  In  a  foreign  species,  (roof7?/<^ra  extreme    thinness    of    the    b;isal 

discolor,  sent  me  by  Mr.  Bateman,  packets   of   pollen,  and  from  tlie 

the  pollinia  approach  in  structure  strength   of  their  attachment  to 

still    more   closely   those  of   the  the  threads,  I  believe  that  they 

Ophreae ;  for  the  pollinia  extend  are   in  a  functionless  condition ; 

into  long  caudicles,  resembling  in  if  so,  these  proloutjations  of  the 

form   those  of  an  Orchis.      The  pollinia  are  true  caudicles. 
caudicle    is    here    formed    of    a 


106  NEOTTE^.  Chap.  IV. 

and  anther, — and  in  some  other  respects,  we  have  a 
clear  affinity  with  Spiranthes.  In  the  anther  having 
a  broad  filament  w^e  see  a  relation  to  Cephalanthera. 
In  the  structure  of  the  rostellum,  with  the  exception 
of  the  sloping  sides,  and  in  the  shape  of  the  labellum, 
Goodyera  resembles  Epipactis.  Goodyera  probably 
shows  us  the  state  of  the  organs  in  a  group  of  Orchids, 
now  mostly  extinct,  but  the  parents  of  many  living 
descendants. 

Spiranthes  aiitumnalis. — This  Orchid  with  its  pretty 
name  of  Ladies'-tresses,  presents  some  interesting 
peculiarities.*  The  rostellum  is  a  long,  thin,  flat  pro- 
jection, joined  by  sloping  shoulders  to  the  summit  of 
the  stigma.  In  the  middle  of  the  rostellum  a  narrow 
vertical  brown  object  (fig.  17,  C)  may  be  seen,  bordered 
and  covered  by  transparent  membrane.  This  brown 
object  I  will  call  "the  boat-formed  disc."  It  forms 
the  middle  portion  of  the  posterior  surface  of  the 
rostellum,  and  consists  of  a  narrow^  strip  of  the  exterior 
membrane  in  a  modified  condition.  When  removed 
from  its  attachment,  its  summit  (fig.  E)  is  seen  to  be 
pointed,  with  the  lower  end  rounded;  it  is  slightly 
bowed,  so  as  altogether  to  resemble  a  boat  or  canoe. 
It  is  rather  more  than  -j-f.-^-  of  an  inch  in  length, 
and  less  than  -p-o-o  '^^  breadth.  It  is  nearly  rigid,  and 
appears  fibrous,  but  is  really  formed  of  elongated 
and  thickened  cells,  partially  confluent. 

This  boat,  standing  vertically  up  on  its  stern,  is  filled 
with  thick,  milky,  extremely  adhesive  fluid,  which, 
when  exposed  to  the  air,  rapidly  turns  brown,  and  in 
about  one  minute  sets  quite  hard.  An  object  is  well 
glued  to  the  boat  in  four  or  five  seconds,  and  when  the 

*  lamindebtefl  toDr.  Battersby       me    specimens.     I    subsequently 
of  Torquay,  and   to  Mr.   A.    G.       examined  many  growing  plants. 
More  of  Bembridtre,  for  sending 


Chap.  IV. 


SPIRANTHES   AUTUMNALIS. 


107 


cement  is  dry  the  attacliment  is  wonderfully  strong. 
The  transparent  sides  of  the  rostellum  consist  of  mem- 
brane, attached  behind  to  the  edges  of  the  boat,  and 
folded  over  in  front,  so  as  to  form  the  anterior  face 
of  the  rostellum.  This  folded  membrane,  therefore, 
covers,  almost  like  a  deck,  the  cargo  of  viscid  matter 
within  the  boat. 

Fig.  17. 


SpIRANTIIES   AUTUMXALIS,    OR    LaDTES'-TrESSES. 


a.    anther. 

p.    pollen-masses. 

t.    threads  of  the  pollen-masses. 

cl.  margin  of  clinandrura. 

r.    rostellum. 

s.     stigma. 

n.    nectar  receptacle. 

A.  Side  view  of  flower  in  its  natural 
position,  with  the  two  lower 
sepals  alone  removed.  The 
label lum  can  be  recognised  by- 
its  fi'inged  and  reflexed  lip. 

^.  Side  view  enlarged  of  a  mature 
flower,  with  all  the  sepals  and 
petals  removed.  The  positions 
of   the   labellum    and    of    the 


upper  sepal  are  shown  by  the 
dotted  Hues. 

C.  Front  view   of  the  stigma,  and 

of  the  rostellum  with  its  em- 
bedded, central,  boat-formed 
disc. 

D.  Front  view  of  the  stigma  and  of 

the  rostellum  after  the  disc  has 
been  removed. 

E.  Disc,  removed  from  the  rostel- 

lum, greatly  enlarged,  viewed 
posteriorly,  with  the  attached 
elastic  threads  of  the  pollen- 
masses  ;  the  pollen-grains  have 
been  removed  from  the  threads. 


The  anterior  face  of  the  rostellum  is  slightly  furrowed 
in  a  longitudinal  line  over  the  middle  of  the  boat,  and 


108  NEOTTE^.  Chap.  IV. 

is  endowed  with  a  remarkable  kind  of  irritability  ; 
for,  if  the  furrow  be  touched  very  gently  by  a  needle, 
or  if  a  bristle  be  laid  along  the  furrow,  it  instantly 
splits  along  its  whole  length,  and  a  little  milky 
adhesive  fluid  exudes.  This  action  is  not  mechanical, 
or  due  to  simple  violence.  The  fissure  runs  up  the 
whole  length  of  the  rostellum,  from  the  stigma  beneath 
to  the  summit :  at  the  summit  the  fissure  bifurcates, 
and  runs  down  the  back  of  the  rostellum  on  each  side 
and  round  the  stern  of  the  boat-formed  disc.  Hence 
after  this  splitting  action  the  boat-formed  disc  lies 
quite  free,  but  embedded  in  a  fork  in  the  rostellum. 
The  act  of  splitting  apparently  never  takes  place 
spontaneously.  I  covered  a  plant  with  a  net,  and  after 
five  of  the  flowers  had  fully  expanded  they  were  kept 
protected  for  a  week :  I  then  examined  their  rostella, 
and  not  one  had  split;  whereas  almost  every  flower 
on  the  surrounding  and  uncovered  spikes,  which  would 
almost  certainly  have  been  visited  and  touched  by 
insects,  had  their  rostella  fissured,  though  they  had 
been  open  for  only  twenty-four  hours.  Exposure  for 
two  minutes  to  the  vapour  of  a  little  chloroform  causes 
the  rostellum  to  split ;  and  this  we  shall  hereafter  see 
is  likewise  the  case  with  some  other  Orchids. 

When  a  bristle  is  laid  for  two  or  three  seconds  in  the 
furrow  of  the  rostellum,  and  the  membrane  has  con- 
sequently become  fissured,  the  viscid  matter  within 
the  boat-formed  disc,  which  lies  close  to  the  surface 
and  indeed  slightly  exudes,  is  almost  sure  to  glue  the 
disc  longitudinally  to  the  bristle,  and  both  are  with- 
drawn together.  When  the  disc,  with  the  pollinia 
attached  to  it,  is  withdrawn,  the  two  sides  of  the  ros- 
tellum (fig.  D),  which  have  been  described  by  some 
botanists  as  two  distinct  foliaceous  projections,  are  left 
sticking  up  like  a  fork.      This  is  the  common  con- 


Chap.  IV.  SPIEANTHES   AUTUMNALIS.  109 

dition  of  the  flowers  after  they  have  been  open  for  a 
day  or  two,  and  have  been  visited  by  insects.  The 
fork  soon  withers. 

Whilst  the  flower  is  in  bud,  the  back  of  the  boat- 
formed  disc  is  covered  with  a  layer- of  large  rounded 
cells,  so  that  the  disc  does  not  strictly  form  the  exterior 
surface  of  the  back  of  the  rostellum.  These  cells 
contain  slightly  viscid  matter :  they  remain  unaltered 
(as  may  be  seen  at  fig.  E)  towards  the  upper  end  of 
the  disc,  but  at  the  point  where  the  pollinia  are  at- 
tached they  disappear.  Therefore  I  at  one  time  con- 
cluded that  the  viscid  matter  contained  in  these  cells, 
when  they  burst,  serve  to  fasten  the  threads  of  the 
pollinia  to  the  disc ;  but,  as  in  several  other  genera, 
in  which  a  similar  attachment  has  to  be  effected,  I 
could  see  no  trace  of  such  cells,  this  view  may  be 
erroneous. 

The  stigma  lies  beneath  the  rostellum,  and  projects 
with  a  sloping  surface,  as  may  be  seen  at  B  in  the 
side-view:  its  lower  margin  is  rounded  and  fringed 
with  hairs.  On  each  side  a  membrane  (d,  B)  extends 
from  the  edges  of  the  stigma  to  the  filament  of  the 
anther,  thus  forming  a  membranous  cup  or  clinandrum, 
in  which  the  lower  ends  of  the  pollen-masses  lie  safely 
protected. 

Each  pollinium  consists  of  two  leaves  of  pollen, 
quite  disconnected  at  their  lower  and  upper  ends,  but 
united  for  about  half  their  length  in  the  middle  by 
elastic  threads.  A  very  slight  modification  would 
convert  the  two  pollinia  into  four  distinct  masses,  as 
occurs  in  the  genus  Malaxis  and  in  many  foreign 
Orchids.  Each  leaf  consists  of  a  double  layer  of 
pollen-grains,  joined  by  fours  together,  and  these 
united  by  elastic  threads,  which  are  more  numerous 
along  the  edges  of  the  leaves,  and  converge  at   the 


110  NEOTTE^.  CuAP.  IV. 

summit  of  the  pollinhim.  The  leaves  are  very  brittle, 
and,  when  placed  on  the  adhesive  stigma,  large  pieces 
are  easily  broken  off. 

Long  before  the  flower  expands,  the  anther-cells, 
which  are  pressed  against  the  back  of  the  rostellum, 
open  in  their  upper  part,  so  that  the  included  pollinia 
come  into  contact  with  the  back  of  the  boat-formed 
disc.  The  projecting  threads  then  become  firmly 
attached  to  rather  above  the  middle  part  of  the  back 
of  the  disc.  The  anther-cells  afterwards  open  lower 
down,  and  their  membranous  walls  contract  and  be- 
come brown ;  so  that  by  the  time  the  flower  is  fully 
expanded  the  upper  part  of  the  pollinia  lie  quite 
naked,  with  their  bases  resting  in  a  little  cup  formed 
by  the  withered  anther-cell,  and  laterally  protected  by 
the  clinandrum.  As  the  pollinia  thus  lie  loose,  they 
are  easily  removed. 

The  tubular  flowers  are  elegantly  arranged  in  a 
spire  round  the  spike,  and  project  from  it  horizontally 
(fig.  A).  The  labellum  is  channelled  down  the  middle, 
and  is  furnished  with  a  reflexed  and  fringed  lip,  on 
which  bees  alight ;  its  basal  internal  angles  are  pro- 
duced into  two  globular  processes,  which  secrete  an 
abundance  of  nectar.  The  nectar  is  collected  (n,  fig. 
B)  in  a  small  receptacle  in  the  lov,^er  part  of  the 
labellum.  Owing  to  the  protuberance  of  the  inferior 
margin  of  the  stigma  and  of  the  two  lateral  inflexed 
nectaries,  the  orifice  into  the  nectar-receptacle  is 
much  contracted.  When  the  flower  first  opens  the 
receptacle  contains  nectar,  and  at  this  period  the 
front  of  the  rostellum,  which  is  slightly  furrowed, 
lies  close  to  the  channelled  labellum ;  consequently 
a  passage  is  left,  but  so  narrow  that  only  a  fine  bristle 
can  be  passed  down  it.  In  a  day  or  two  the  column 
moves  a  little  farther  from  the  labellum,  and  a  wider 


Chap.  IV.  SPIRANTHES  AUTUMNALIS.  Ill 

passage  is  left  for  insects  to  deposit  pollen  on  the 
stigmatic  surface.  On  this  slight  movement  of  the 
column  the  fertilisation  of  the  flower  absolutely 
depends.* 

With  most  Orchids  the  flowers  remain  open  for 
some  time  before  they  are  visited  by  insects;  but 
with  Spiranthes  I  have  generally  found  the  boat- 
formed  discs  removed  very  soon  after  their  expansion. 
For  example,  in  the  two  last  spikes  which  I  happened 
to  examine  there  were  numerous  buds  on  the  summit 
of  one,  with  only  the  seven  lowest  flowers  expanded, 
of  which  six  had  their  discs  and  pollinia  removed; 
the  other  spike  had  eight  expanded  flowers,  and  the 
pollinia  of  all  were  removed.  We  have  seen  that  when 
the  flowers  first  open  they  would  be  attractive  to 
insects,  for  the  receptacle  already  contains  nectar; 
and  at  this  period  the  rostellum  lies  so  close  to  the 
channelled  labellum  that  a  bee  could  not  pass  down 
its  proboscis  without  touching  the  medial  furrow  of 
the  rostellum.  This  I  know  to  be  the  case  by  repeated 
trials  with  a  bristle. 

We  thus  see  how  beautifully  everything  is  contrived 
that  the  pollinia  should  be  withdrawn  by  insects  visit- 
in  o-  the  flowers.  They  are  already  attached  to  the 
disc  by  their  threads,  and,  from  the  early  withering 
of  the  anther-cells,  they  hang  loosely  suspended  but 
protected  within  the  clinandrum.     The  touch  of  the 

♦  Profeasor  Asa   Gray  was  so  of  all  the  parts  in  Spirantlies  with 

kind  as  to  examine  for  me  Spi-  the  exception  that  it  is  the  column 

ranthes  qradUs  and  cernua  in  the  atid  not  the  labellum,  as  I  formrr- 

United    States.      He    found    the  ly  thought,  which  moves  as  the 

same  general  structure  as  in  our  flowers  becomematu-e^    He  adds 

8.    autumnalis,   and   was    struck  that  the  widening  oi  the  passage, 

with  the  narrowness  of  the  passage  which  plays  so  important  a  part 

into    the    flower.     He   hns   since  in  the  fe.tihsation  of  the  flower, 

confirmed      ('Amer.     Journ.     of  "  is   so   striking  t^iat  we  wundei 

Science/  vol.  xxxiv.  p.  427)  my  how  we  overlooked  it. 
account  of  the  structure  and  action 


1 12  NEOTTEiB.  Chap.  IV. 

proboscis  causes  the  rostellum  to  sj)Iit  in  front  and 
behind,  and  frees  the  long,  narrow,  boat-formed  disc, 
wliich  is  filled  with  extremely  viscid  matter,  and  is  sure 
to  adhere  longitudinally  to  the  proboscis.  When  the 
bee  flies  away,  so  surely  will  it  carry  away  the  pollinia. 
As  the  pollinia  are  attached  parallel  to  the  disc,  they 
adhere  parallel  to  the  proboscis.  When  the  flower 
first  opens  and  is  best  adapted  for  the  removal  of  the 
pollinia,  the  labellum  lies  so  close  to  the  rostellum, 
that  the  pollinia  attached  to  the  proboscis  of  an  insect 
cannot  possibly  be  forced  into  the  passage  so  as  to 
reach  the  stigma ;  they  would  be  either  upturned  or 
broken  off:  but  we  have  seen  that  after  two  or  three 
days  the  column  becomes  more  reflexed  and  moves 
from  the  labellum, — a  wider  passage  being  thus  left. 
When  I  inserted  the  pollinia  attached  to  a  fine  bristle 
into  the  nectar-recej)tacle  of  a  flower  in  this  condition 
(n,  fig.  B),  it  was  pretty  to  see  how  surely  the  sheets 
of  pollen  were  left  adhering  to  the  viscid  stigma.  It 
may  be  observed  in  the  diagram,  B,  that  owing  to  the 
projection  of  the  stigma,  the  orifice  into  the  nectar- 
receptacle  (n)  lies  close  to  the  lower  side  of  the  flower ; 
insects  would  therefore  insert  their  proboscides  along 
this  lower  side,  and  an  open  space  above  is  thus  left 
for  the  attached  pollinia  to  be  carried  down  to  the 
stigma,  without  being  brushed  off.  The  stigma  evi- 
dently projects  so  that  the  ends  of  the  pollinia  may 
strike  against  it. 

Hence,  in  Spiranthes,  a  recently  expanded  flower, 
which  has  its  pollinia  in  the  best  state  for  removal, 
cannot  be  fertilised ;  and  mature  flowers  will  be  ferti- 
lised by  pollen  from  younger  flowers,  borne,  as  we 
shall  presently  see,  on  a  separate  plant.  In  con- 
formity with  this  fact  the  stigmatic  surfaces  of  the 
older  flowers  are  far  more   viscid   than  those  of  the 


Chap.  IV.  SPIRANTHES  AUTUMNALIS.  113 

younger  flowers.  Nevertheless,  a  flower  which,  in  its 
early  state  had  not  been  visited  by  insects  would  not 
necessarily,  in  its  later  and  more  expanded  condition, 
have  its  pollen  wasted :  for  insects,  in  inserting  and 
withdrawing  their  proboscides,  bow  them  forwards  or 
upwards,  and  would  thus  often  strike  the  furrow  in  the 
rostellum.  I  imitated  this  action  with  a  bristle,  and 
often  succeeded  in  withdrawing  the  pollinia  from  old 
flowers.  I  was  led  to  make  this  trial  from  having  at 
first  chosen  old  flowers  for  examination ;  and  on  passing 
a  bristle,  or  fine  culm  of  grass,  straight  down  into 
the  nectary,  the  pollinia  were  never  withdrawn ;  but 
when  it  was  bowed  forward,  I  succeeded.  Flowers 
which  have  not  had  their  pollinia  removed  can  be 
fertilised  as  easily  as  those  which  have  lost  them ;  and 
I  have  seen  not  a  few  cases  of  flowers  with  their 
pollinia  still  in  place,  with  sheets  of  pollen  on  their 
stigmas. 

At  Torquay  I  watched  for  about  half  an  hour  a 
number  of  these  flowers  growing  together,  and  saw 
three  humble-bees  of  two  kinds  visit  them.  I  caught 
one  and  examined  its  proboscis :  on  the  superior 
lamina,  some  little  way  from  the  tip,  two  perfect 
pollinia  were  attached,  and  three  other  boat-formed 
discs  without  pollen ;  so  that  this  bee  had  removed 
the  pollinia  from  five  flowers,  and  had  probably  left 
the  pollen  of  three  on  the  stigmas  of  other  flowers. 
The  next  day  I  watched  the  same  flowers  for  a  quarter 
of  an  hour,  and  caught  another  humble-bee  at  work ; 
one  perfect  pollinium  and  four  boat-formed  discs  ad- 
hered to  its  proboscis,  one  on  the  top  of  the  other, 
showing  how  exactly  the  same  part  of  the  rostellum 
had  each  time  been  touched. 

The  bees  always  alighted  at  the  bottom  of  the 
spike,  and,  crawling  spirally  up  it,  sucked  one  flower 


114  NEOTTE^.  CHiP.  IV. 

after  ttie  other.  1  believe  humble-bees  generally  act 
in  this  manner  when  visiting  a  dense  spike  of  flowers, 
as  it  is  the  most  convenient  method  ;  on  the  same 
principle  that  a  woodpecker  always  climbs  up  a  tree  in 
search  of  insects.  This  seems  an  insignificant  observa- 
tion ;  but  see  the  result.  In  the  early  morning,  when 
the  bee  starts  on  her  rounds,  let  us  suppose  that  she 
alighted  on  the  summit  of  a  spike ;  she  would  cer- 
tainly extract  the  poUinia  from  the  uppermost  and 
last  opened  flowers ;  but  when  visiting  the  next  suc- 
ceeding flower,  of  which  the  column  in  all  probability 
would  not  as  yet  have  moved  from  the  labellum  (for 
this  is  slowly  and  very  gradually  effected),  the  pollen- 
masses  would  be  brushed  off  her  proboscis  and  wasted. 
But  nature  suffers  no  such  waste.  The  bee  goes  first 
to  the  lowest  flower,  and,  crawling  spirally  up  the 
spike,  effects  nothing  on  the  first  spike  which  she 
visits  till  she  reaches  the  upper  flowers,  and  then  she 
withdraws  the  pollinia.  She  soon  flies  to  another  plant, 
and,  alighting  on  the  lowest  and  oldest  flower,  into 
which  a  wide  passage  will  have  been  formed  from  the 
greater  reflexion  of  the  column,  the  pollinia  strike  the 
protuberant  stigma.  If  the  stigma  of  the  lowest  flower 
has  already  been  fully  fertilised,  little  or  no  pollen 
will  be  left  on  its  dried  surface ;  but  on  the  next 
succeeding  flower,  of  which  the  stigma  is  adhesive, 
large  sheets  of  pollen  will  be  left.  Then  as  soon  as 
the  bee  arrives  near  the  summit  of  the  spike  she  will 
withdraw  fresh  pollinia,  will  fly  to  the  lower  flowers 
on  another  plant,  and  fertilise  them ;  and  thus,  as  she 
goes  her  rounds  and  adds  to  her  store  of  honey,  she 
continually  fertilises  fresh  flowers  and  perpetuates  the 
race  of  our  autumnal  Spiranthes,  which  will  yield 
honey  to  future  generations  of  bees. 

Spiranthes   australis. — This   species,   an   inhabitant 


Chap.  IV.  LISTERA  OVATA.  115 

of  Australia,  lias  been  described  and  figured  by  Mr. 
Fitzgerald.*  The  flowers  are  arranged  on  the  spike 
in  the  same  manner  as  in  S.  autumnalis ;  and  the 
labellum  with  two  glands  at  its  base  closely  resembles 
that  of  our  species.  It  is  therefore  an  extraordinary 
fact  that  Mr.  Fitzgerald  could  not  detect  even  in  the 
bud  any  trace  of  a  rostellum  or  of  viscid  matter.  He 
states  that  the  pollinia  touch  the  upper  edge  of  the 
stigma,  and  fertilise  it  at  an  early  age.  Protecting  a 
plant  from  the  access  of  insects  by  a  bell-glass  made 
no  difference  in  its  fertility ;  and  Mr.  Fitzgerald, 
though  he  examined  many  flowers,  never  noticed  the 
slightest  derangement  of  the  pollinia,  or  any  pollen 
on  the  surfaces  of  the  stigmas.  Here  then  we  have 
a  species  which  fertilises  itself  as  regularly  as  does 
Ophrijs  apifera.  It  would,  however,  be  desirable  to 
ascertain  whether  insects  ever  visit  the  flowers,  which 
it  may  be  presumed  secrete  nectar,  as  glands  are 
present ;  and  any  such  insects  should  be  examined,  so 
as  to  make  certain  that  pollen  does  not  adhere  to  some 
part  of  their  bodies. 

Listera  ovafa,  or  Tivay-Uade, — This  Orchid  is  one 
of  the  most  remarkable  in  the  whole  order.  The 
structure  and  action  of  the  rostellum  has  been  the 
subject  of  a  valuable  paper  in  the  *  Philosophical 
Transactions,'  by  Dr.  Hooker,t  who  has  described 
minutely  and  of  course  correctly  its  curious  structure  ; 
he  did  not,  however,  attend  to  the  part  which  insects 
play  in  the  fertilisation  of  the  flowers.  C.  K.  Sprengel 
well  knew  the  importance  of  insect-agency,  but  he 
misunderstood  both  the  structure  and  the  action  of 
the  rostellum. 

The  rostellum  is  of  large  size,  thin,  or  foliaceous, 

•  'Australian  Orchids.' part  ii.  t  *  Philosophical  Transactions,' 

1876.  1854,  p.  259. 


116 


NEOTTE^. 


Chap.  IV, 


convex  in  front  and  concave  behind,  with  its  sharp 
summit  slightly  hollowed  out  on  each  side ;  it  arches 
over  the  stigmatic  surface  (fig.  18,  A,  r,  s).    Internally, 

Fig,  18. 


LiSTERA  OVATA,  or  Tvvay-blade.     (Partly  copied  from  Hooker.; 


col. 

summit  of  column. 

A.    Flower  viewed  laterally,  with 

a. 

dnther. 

all  the  sepals  and  petals,  except 

V' 

pollen. 

the  labellum,  removed. 

r. 

rostellum. 

B.    Ditto,    with    the    pollinia    re- 

s. 

stigma. 

moved,  and  with  the  rostellum 

/. 

labellum. 

bent   down  after  the  ejection 

n. 

nectar-secreting  furrow. 

of  the  viscid  matter. 

Chap.  IV. 


LISTERA  OVATA.  117 


it  is  divided  by  longitudinal  septa  into  a  series  of 
loculi,  which  contain  viscid  matter  and  have  the  power 
of  violently  expelling  it.  These  loculi  show  traces  of 
their  original  cellular  structure.  I  have  met  with  this 
structure  in  no  other  genus  except  in  the  closely 
allied  Neottia.  The  anther,  situated  behind  the  ros- 
tellum  and  protected  by  a  broad  expansion  of  the  top 
of  the  column,  opens  in  the  bud.  When  the  flower  is 
fully  expanded,  the  pollinia  are  left  quite  free,  sup- 
ported behind  by  the  anther-cells,  and  lying  in  front 
against  the  concave  back  of  the  rostellum,  with  their 
upper  pointed  ends  resting  on  its  crest.  Each  pol- 
linium  is  almost  divided  into  two  masses.  The  pollen- 
grains  are  attached  together  in  the  usual  manner  by 
a  few  elastic  threads ;  but  the  threads  are  weak,  and 
large  masses  of  pollen  can  be  broken  off  easily.  After 
the  flower  has  long  remained  open,  the  pollen  becomes 
more  friable.  The  labellum  is  much  elongated,  con- 
tracted at  its  base,  and  bent  downwards,  as  represented 
in  the  drawing  ;  the  upper  half  above  the  bifurcation 
is  furrowed  along  the  middle ;  and  the  borders  of  this 
furrow  secrete  much  nectar. 

As  soon  as  the  flower  opens,  if  the  crest  of  the 
rostellum  be  touched  ever  so  lightly,  a  large  drop 
of  viscid  fluid  is  instantaneously  expelled  ;  and  this, 
as  Dr.  Hooker  has  shown,  is  formed  by  the  coalescence 
of  two  drops  proceeding  from  two  depressed  spaces  on 
each  side  of  the  centre.  A  good  proof  of  this  fact 
was  afforded  by  some  specimens  kept  in  weak  spirits 
of  wine,  which  apparently  had  expelled  the  viscid 
matter  slowly,  and  here  two  separate  little  spherical 
balls  of  hardened  matter  had  been  formed,  attached  to 
the  two  pollinia.  The  fluid  is  at  first  slightly  opaque 
and  milky ;  but  on  exposure  to  the  air  for  less  than 
a  second,  a  film  forms  over  it,  and  in  two   or   three 


118  NE0TTE2E.  Chap.  IV. 

seconds  the  whole  drop  sets  hard,  soon  assuming  a 
purplish-brown  tint.  So  exquisitely  sensitive  is  the 
rostellum,  that  a  touch  from  the  thinnest  human  hair 
suffices  to  cause  the  explosion.  It  will  take  place 
under  water.  Exposure  to  the  vapour  of  chloroform 
for  about  one  minute  also  caused  an  explosion;  but 
the  vapour  of  sulphuric  ether  did  not  thus  act,  though 
one  flower  was  exposed  for  five,  and  another  for 
twenty  minutes  to  a  strong  dose.  The  rostellum  of 
these  two  flowers  when  afterwards  touched  exploded  in 
the  usual  manner,  so  that  sensitiveness  had  not  been 
lost  in  either  case.  The  viscid  fluid  when  pressed 
between  two  plates  of  glass  before  it  has  set  hard  is 
seen  to  be  structureless ;  but  it  has  a  reticulated 
appearance,  perhaps  caused  by  the  presence  of  glo- 
bules of  a  denser  immersed  in  a  thinner  fluid.  As  the 
pointed  tips  of  the  poUinia  lie  on  the  crest  of  the 
rostellum,  they  are  always  caught  by  the  exploded 
drop  :  I  have  never  seen  this  once  to  fail.  So  rapid 
is  the  explosion  and  so  viscid  the  fluid,  that  it  is 
difficult  to  touch  the  rostellum  with  a  needle,  however 
quickly  this  may  be  done,  without  removing  the 
poUinia.  Hence,  if  a  bunch  of  flowers  be  carried 
home  in  the  hand,  some  of  the  sepals  or  petals  will 
almost  certainly  touch  the  rostellum  and  withdraw  the 
poUinia ;  and  this  gives  the  false  appearance  of  their 
having  been  ejected  to  a  distance. 

After  the  anther-cells  have  opened  and  the  naked 
poUinia  have  been  left  resting  on  the  concave  back  of 
the  rostellum,  this  latter  organ  curves  a  little  forwards, 
and  perhaps  the  anther  also  moves  a  little  backwards. 
This  movement  is  of  much  importance ;  if  it  did  not 
occur,  the  tip  of  the  anther,  within  which  the  poUinia 
are  lodged,  would  be  caught  by  the  exploded  viscid 
matter,  and  the  poUinia  would  be  for  ever  locked  up 


Chap.  IV.  LISTEEA   OVATA. 


119 


and  rendered  useless.  I  once  found  an  injured  flower 
which  had  been  pressed  and  had  exploded  before  fully 
expanding,  and  the  anther  with  the  enclosed  pollen- 
masses  was  permanently  glued  to  the  crest  of  the  ros- 
tellum.  The  rostellum,  which  is  naturally  somewhat 
arched  over  the  stigma,  quickly  bends  forwards  and 
downwards  at  the  moment  of  the  explosion,  so  as  then 
to  stand  (fig.  B)  at  right  angles  to  the  surface  of  the 
stigma.  The  pollinia,  if  not  removed  by  the  touching 
object  which  causes  the  explosion,  become  fixed  to  the 
rostellum,  and  by  its  movement  are  likewise  drawn  a 
little  forward.  If  their  lower  ends  are  now  freed  by  a 
needle  from  the  anther-cells,  they  spring  up ;  but  they 
are  not  by  this  movement  placed  on  the  stigma.  In 
the  course  of  some  hours,  or  of  a  day,  the  rostellum 
not  only  slowly  recovers  its  original  slightly-arched 
position,  but  becomes  quite  straight  and  parallel  to 
the  stigmatic  surface.  This  backward  movement  of 
the  rostellum  is  of  service  ;  for  if  after  the  explosion  it 
had  remained  permanently  projecting  at  right  angles 
over  the  stigma,  pollen  could  not  readily  have  been 
deposited  by  insects  on  the  viscid  surface  of  the 
stigma.  When  the  rostellum  is  touched  so  quickly 
that  the  pollinia  are  not  removed,  they  are,  as  I  have 
just  said,  drawn  a  little  forward  ;  but  by  the  subse- 
quent backward  movement  of  the  rostellum  they  are 
pushed  back  again  into  their  original  position. 

From  the  account  now  given  we  may  safely  infer 
how  the  fertilisation  of  this  Orchid  is  effected.  Small 
insects  alight  on  the  labellum  for  the  sake  of  the 
nectar  copiously  secreted  by  it ;  as  they  lick  this  they 
slowly  crawl  up  its  narrowed  surface  until  their  heads 
stand  directly  beneath  the  overarching  crest  of  the 
rostellum ;  when  they  raise  their  heads  they  touch  the 
crest ;  this  then  explodes,  and  the  pollinia  are  instantly 


120  NEOTTE^.  Chap.  IV 

and  firmly  cemented  to  tlieir  heads.  As  soon  as  tlie 
insect  flies  away,  it  withdraws  the  poUinia,  carries 
them  to  another  flower,  and  there  leaves  masses  of  the 
friable  pollen  on  the  adhesive  stigma. 

In  order  to  witness  what   I   felt   sure  would   take 
place,  I  watched   for  an  hour  a  group  of  plants  on 
three   occasions;    each  time   I   saw   numerous   speci- 
mens of  two  small  Hymenopterous  insects,  namely,  a 
Haemiteles  and  a  Cryptus,  flying  about  the  plants  and 
licking  up  the  nectar  ;  most  of  the  flowers,  which  were 
visited  over  and  over  again,  already  had  their  pollinia 
removed,  but  at  last  I  saw  both  these  species  crawl 
into  younger  flowers,  and  suddenly  retreat  with  a  pair 
of  bright  yellow  pollinia  sticking  to  their  foreheads  ;  I 
caught  them,  and  found  the  point  of  attachment  was  to 
the  inner  edge  of  the  eye;  on  the  other  eye  of* one 
specimen  there   was   a   ball   of  the   hardened   viscid 
matter,   showing    that   it    had    previously    removed 
another  pair  of  pollinia,  and  in  all  probability  had  subse- 
quently left  them  on  the  stigma  of  a  flower.     As  these 
insects  were  captured,  I  did  not  witness  the  act  of  fertili- 
sation ;   but   Sprengel   saw  a  Hymenopterous  insect 
leave  its  pollen-mass  on  the  stigma.     My  son  watched 
another  bed  of  this  Orchid  at  some  miles'  distance,  and 
brought  me  home  the  same  Hymenopterous  insects 
with    attached   pollinia,   and    he    saw   Diptera    also 
visiting  the  flowers.     He  was  struck  with  the  number 
of  spider-webs   spread  over  these   plants,  as  if    the 
spiders  were  aware  how  attractive  the  Listera  was  to 
insects. 

To  show  how  delicate  a  touch  suffices  to  cause 
the  rostellum  to  explode,  I  may  mention  that  I  found 
an  extremely  minute  Hymenopterous  insect  vainly 
struggling  to  escape,  with  its  head  cemented  by  the 
hardened  viscid  matter,  to  the  crest  of  the  rostellum 


Chap.  IV.  LISTEEA  OVATA.  121 

and  to  the  tips  of  the  pollinia.  The  insect  was  not 
so  large  as  one  of  the  pollinia,  and  after  causing  the 
explosion  had  not  strength  enough  to  remove  them ; 
it  was  thus  punished  for  attempting  a  work  beyond 
its  strength,  and  perished  miserably. 

In  Spiranthes  the  young  flowers,  which  have  their 
pollinia  in  the  best  state  for  removal,  cannot  possibly 
be  fertilised ;  they  must  remain  in  a  virgin  condition 
until  they  are  a  little  older  and  the  column  has 
moved  away  from  the  labellum.  Here  the  same  end 
is  gained  by  widely  different  means.  The  stigmas  of 
the  older  flowers  are  more  adhesive  than  those  of  the 
younger  flowers.  These  latter  have  their  pollinia 
ready  for  removal ;  but  immediately  after  the  rostellum 
has  exploded,  it  curls  forwards  and  downwards,  thus 
protecting  the  stigma  for  a  time;  but  it  slowly  be- 
comes straight  again,  and  now  the  mature  stigma  is 
left  freely  exposed,  ready  to  be  fertilised. 

I  wished  to  know  whether  the  rostellum  would 
explode,  if  never  touched ;  but  I  have  found  it  difficult 
to  ascertain  this  point,  as  the  flowers  are  highly  at- 
tractive to  insects,  and  it  is  scarcely  possible  to  exclude 
very  minute  ones,  the  touch  of  which  suffices  to  cause 
the  explosion.  Several  plants  were  covered  by  a  net 
and  left  till  the  surrounding  plants  had  set  their 
capsules ;  and  the  rostella  in  most  of  the  covered-up 
flowers  were  found  not  to  have  exploded,  though  their 
stigmas  were  withered,  and  the  pollen  mouldy  and 
incapable  of  removal.  Some  few  of  the  very  old 
flowers,  however,  when  roughly  touched,  were  still 
capable  of  a  feeble  explosion.  Other  flowers  under 
the  nets  had  exploded,  and  they  had  the  tips  of  their 
pollinia  fixed  to  the  crest  of  the  rostellum  ;  but  whether 
these  had  been  touched  by  some  minute  insect,  or  had 
exploded  spontaneously,  it  was  impossible   to  deter- 


122  NEOTTE^.  Chap.  IV 

mine.  It  should  be  observed,  that  although  I  looked 
carefully,  not  a  grain  of  pollen  could  be  found  on  the 
stigmas  of  any  of  these  flowers,  and  their  ovaria  had 
not  swollen.  During  a  subsequent  year,  several  plants 
were  again  covered  by  a  net,  and  I  found  that  the 
rostellum  lost  its  power  of  explosion  in  about  four 
days ;  the  viscid  matter  having  turned  brown  within 
the  loculi  of  the  rostellum.  The  weather  at  the  time 
was  unusually  hot,  and  this  probably  hastened  the 
process.  After  the  four  days  the  pollen  had  become 
very  incoherent,  and  some  had  fallen  on  the  tv/o 
corners,  and  even  over  the  whole  surface  of  the  stigma, 
which  was  penetrated  by  the  pollen-tubes.  But  the 
scattering  of  the  pollen  was  largely  aided  by,  and 
perhaps  wholly  depended  on,  the  presence  of  Thrips 
— insects  so  minute  that  they  could  not  be  excluded 
by  any  net,  and  which  abounded  on  the  flowers.  This 
plant,  therefore,  is  capable  of  occasional  self-fertilisa- 
tion, if  the  access  of  winged  insects  be  prevented  ;  but 
I  have  every  reason  to  believe  that  this  occurs  very 
rarely  in  a  state  of  nature. 

That  insects  do  their  work  of  cross-fertilisation 
efi'ectually  is  shown  by  the  following  cases.  The 
seven  upper  flowers  on  a  young  spike  with  many 
unexpanded  buds,  still  retained  their  pollinia,  but 
these  had  been  removed  from  the  ten  lower  flowers ; 
and  there  was  pollen  on  the  stigmas  of  six  of  them. 
In  two  spikes  taken  together,  the  twenty-seven  lower 
flowers  all  had  their  pollinia  removed,  and  had  pollen 
on  their  stigmas;  these  were  succeeded  by  five  open 
flowers  with  the  pollinia  not  removed  and  without  any 
pollen  on  the  stigmas  ;  and  these  were  succeeded  by 
eighteen  buds.  Lastly,  in  an  older  spike  with  forty- 
four  fully  expanded  flowers,  the  pollinia  had  been 
removed  from  everv  single  one  ;  and  tliere  was  pollen. 


Chap.  IV.  LISTER  A  OVATA.  123 

generally  in  large  quantity,  on  all  the  stigmas  which 
I  examined. 

I  will  recapitulate  the  several  special  adaptations 
for  the  fertilisation  of  this  plant.  The  anther-cells 
open  early,  leaving  the  pollen-masses  free,  protected 
by  the  summit  of  the  column,  and  with  their  tips 
resting  on  the  concave  crest  of  the  rostellum.  The 
rostellum  then  slowly  curves  over  the  stigmatic 
surface,  so  that  its  explosive  crest  stands  at  a  little 
distance  from  the  summit  of  the  anther;  and  this 
is  very  necessary,  otherwise  the  summit  would  be 
caught  by  the  viscid  matter,  and  the  pollen  for  ever 
locked  up.  The  curvature  of  the  rostellum  over  the 
stigma  and  over  the  base  of  the  labellum  is  excellently 
adapted  to  favour  an  insect  striking  the  crest  when  it 
raises  its  head,  after  having  crawled  up  the  labellum 
and  licked  the  last  drop  of  nectar.  The  labellum,  as 
C.  K.  Sprengel  has  remarked,  becomes  narrower  where 
it  joins  the  column  beneath  the  rostellum,  so  that 
there  is  no  risk  of  an  insect  going  too  much  to  either 
side.  The  crest  of  the  rostellum  is  so  exquisitely 
sensitive,  that  a  touch  from  a  very  minute  insect 
causes  it  to  rupture  at  two  points,  and  instantly  two 
drops  of  viscid  Huid  are  expelled,  which  coalesce.  This 
viscid  fluid  sets  hard  in  so  wonderfully  rapid  a  manner 
that  it  rarely  fails  to  cement  the  tips  of  the  pollinia, 
nicely  laid  on  the  crest  of  the  rostellum,  to  the  fore- 
head of  the  touching  insect.  As  soon  as  the  rostellum 
has  exploded  it  suddenly  curves  downwards  so  as  to 
project  at  right  angles  over  the  stigma,  protecting  it 
from  impregnation  at  an  early  age,  in  the  same  manner 
as  the  stigmas  of  the  young  flowers  of  Spiranthes  are 
protected  by  the  labellum  clasping  the  column.  But 
as  the  column  of  Spiranthes  after  a  time  moves  from 
the  labellum,  leaving  a  free  passage  for  the  introduc* 


124  NEOTTE^.  Chap.  IV. 

tion  of  the  pollinia,  so  here  the  rostellum  moves  back- 
wards, and  not  only  recovers  its  former  arched  position, 
but  stands  upright,  leaving  the  stigmatic  surface,  now 
rendered  more  adhesive,  perfectly  free  for  pollen  to  be 
left  on  it.  The  pollen-masses,  when  once  cemented  to 
an  insect's  forehead,  will  remain  attached  to  it,  until 
they  are  brought  into  contact  with  the  stigma  of  a 
mature  flower ;  and  then  these  encumbrances  will  be 
removed,  by  the  rupturing  of  the  weak  elastic  threads 
which  tie  the  grains  together ;  the  flower  being  at  tlie 
same  time  fertilised. 

Listera  cordata. — Professor  Dickie  of  Aberdeen  was 
so  kind  as  to  send  me,  but  rather  too  late  in  the 
season,  two  sets  of  specimens.  The  flowers  have  essen- 
tially the  same  structure  as  in  the  last  species.  The 
loculi  of  the  rostellum  are  very  distinct.  Two  or  three 
little  hairy  points  project  from  the  middle  of  the  crest 
of  the  rostellum ;  but  I  do  not  know  whether  these 
have  any  functional  importance.  The  labellum  has 
two  basal  lobes  (of  which  vestiges  may  be  seen  in 
L.  ovata)  which  curve  up  on  each  side  ;  and  these 
would  compel  an  insect  to  approach  the  rostellum 
straight  in  front.  In  two  of  the  flowers  the  pollinia 
were  firmly  cemented  to  the  crest  of  the  rostellum ; 
but  in  almost  all  the  others  the  pollinia  had  been 
previously  removed  by  insects. 

In  the  following  year  Professor  Dickie  observed  the 
flowers  on  living  plants,  and  he  informs  me  that,  when 
the  pollen  is  mature,  the  crest  of  the  rostellum  is 
directed  towards  the  labellum,  and  that,  as  soon  as 
touched,  the  viscid  matter  explodes,  the  pollinia  becom- 
ing attached  to  the  touching  object ;  after  the  explosion, 
the  rostellum  bends  downwards,  thus  protecting  the 
virgin  stigmatic  surface ;  subsequently  it  rises  up  and 
exposes  the  stigma ;  sc  that  here  everything  goes  on 


Chap.  IV.  NEOTTIA   NIDUS- A  VIS.  125 

as  1  have  described  under  Listera  ovata.     The  flowers 
are  frequented  by  minute  Diptera  and  Hymenoptera. 

Neottia  nidus-avis. — I  made  numerous  observations 
on  this  plant,  the  Bird's-nest  Orchis,*  but  they  are  not 
worth  giving,  as  the  action  and  structure  of  every 
part  is  almost  identically  the  same  as  in  Listera  ovata 
and  eordata.  On  the  crest  of  the  rostellum  there  are 
about  six  minute  rough  points,  which  seem  particularly 
sensitive  to  a  touch,  causing  the  expulsion  of  the 
viscid  matter.  The  exposure  of  the  rostellum  to  the 
vapour  of  sulphuric  ether  for  twenty  minutes  did  not 
prevent  this  action,  when  it  was  touched.  The  label- 
lum  secretes  plenty  of  nectar,  which  I  mention  merely 
as  a  caution,  because  during  one  cold  and  wet  season 
I  looked  several  times  and  could  not  see  a  drop,  and 
was  perplexed  at  the  apparent  absence  of  any  attrac- 
tion for  insects  ;  nevertheless,  had  I  looked  more  per- 
severingly,  perhaps  I  should  have  found  some. 

The  flowers  must  be  freely  visited  by  insects,  for 
all  in  one  large  spike  had  their  pollinia  removed. 
Another  unusually  fine  spike,  sent  me  by  Mi.  Oxenden 
from  South  Kent,  had  borne  forty-one  flowers,  and  it 
produced  twenty-seven  large  seed-capsules,  besides 
some  smaller  ones.  Dr.  H.  Miiller  of  Lippstadt  in- 
forms me  that  he  has  seen  Diptera  sucking  the  nectar 
and  removing  the  pollinia. 

The  pollen-masses  resemble  those  of  Listera,  in 
consisting  of  compound  grains  tied  together  by  a  few 
weak  threads  ;  they  differ  in  being  much  more  inco- 
herent ;  after  a  few  days  they  swell  and  overhang  the 
sides  and  summit  of  the  rostellum ;  so  that  if  the  ros- 
tellum of  a  rather  old  flower  be  touched  and  an  explo- 


*  This  unnatural  sickly- looking  lives ;   but,  acoording  to  Irmisch 

plant  Las  generally  been  "supposed  ('  Beitrage  zur  Biologic  und  Mor- 

to  b'  parasitic  on  rhe  roots  of  tlie  pliologie  der  Orchideen,'  1853,  s. 

trees  under  the  shade  of  which  it  25),  this  certainly  is  not  the  case. 


126  NEOTTE^.  Chap.  IV. 

sion  caused,  the  pollen-masses  are  not  so  neatly  caught 
by  their  tips  as  those  of  Listera.  Thus  a  good  deal  of 
the  friable  pollen  is  often  left  behind  in  the  anther- 
cells  and  is  apparently  wasted.  Several  plants  were 
protected  from  the  access  of  winged  insects  by  a  net, 
and  after  four  days  the  rostella  had  almost  lost  their 
sensitiveness  and  power  to  explode.  The  pollen  had 
become  extremely  incoherent,  and  in  all  the  flowers 
much  had  fallen  on  the  stigmas  which  were  penetrated 
by  the  pollen-tubes.  The  spreading  of  the  pollen 
seems  to  be  in  part  caused  by  the  presence  of  Thrips, 
many  of  which  minute  insects  were  crawling  about  the 
flowers,  dusted  all  over  with  pollen.  The  covered-up 
plants  produced  plenty  of  capsules,  but  many  of  these 
were  much  smaller  and  contained  fewer  seeds  than 
those  produced  by  the  adjoining  uncovered  plants. 

If  insects  had  been  forced  by  the  labellum  being 
more  upturned  to  brush  against  the  anther  and  stigma, 
they  would  always  have  been  smeared  with  the  pollen 
as  soon  as  it  became  friable ;  and  they  would  thus 
have  fertilised  the  flowers  effectually  without  the  aid 
of  the  explosive  rostellum.  This  conclusion  interested 
me,  because,  when  previously  examining  Cephalan- 
thera,  with  its  aborted  rostellum,  its  upturned  label- 
lum and  friable  pollen,  I  had  speculated  how  a  transi- 
tion, with  each  gradation  useful  to  the  plant,  could 
have  been  effected  from  the  state  of  the  pollen  in  the 
similarly  constructed  flowers  of  Epipactis,  with  their 
pollinia  attached  to  a  well-developed  rostellum,  to  the 
present  condition  of  Cephalanthera.  Neottia  nidus- 
avis  shows  us  how  such  a  transition  might  have  been 
efi'ected.  This  Orchid  is  at  present  mainly  fertilised 
by  means  of  the  explosive  rostellum,  which  acts  effec- 
tually only  as  long  as  the  pollen  remains  in  mass ; 
but  we  have  seen  that  as  the  flower  grows  old  the 
pollen  swells  aud  becomes  friable,  and  is  then  apt  to 


Chap.  IV.  THELYMITRA.  127 

fall  or  be  transported  by  rainute  crawling  insects  on 
to  the  stigma.  By  this  means  self-fertilisation  is 
assured,  should  larger  insects  fail  to  visit  the  flowers. 
Moreover,  the  pollen  in  this  state  readily  adheres  to 
any  object;  so  that  by  a  slight  change  in  the  shape  of 
the  flower,  which  is  already  less  open  or  more  tubular 
than  that  of  Listera,  and  by  the  pollen  becoming 
friable  at  a  still  earlier  age,  its  fertilisation  would  be 
rendered  more  and  more  easy  without  the  aid  of  the 
explosive  rostellum.  Ultimately  it  would  become  a 
superfluity ;  and  then,  on  the  principle  that  every  part 
which  is  not  brought  into  action  tends  to  disappear, 
from  causes  which  I  have  elsewhere  endeavoured  to 
explain,*  this  would  happen  with  the  rostellum.  We 
should  then  see  a  new  species,  in  the  condition  of 
Cephalanthera  as  far  as  its  means  of  fertilisation  were 
concerned,  but  in  general  structure  closely  allied  to 
Neottia  and  Listera. 

Mr.  Fitzgerald,  in  the  introduction  to  his  *  Austra- 
lian Orchids,'  says  that  Thelymitra  carnea,  one  of 
the  Neottea3,  invariably  fertilises  itself  by  means  of  the 
incoherent  pollen  falling  on  the  stigma.  Nevertheless 
a  viscid  rostellum,  and  other  structures  adapted  for 
cross-fertilisation  are  present.  The  flowers  seldom 
expand,  and  never  until  they  have  fertilised  them- 
selves ;  so  that  they  seem  tending  towards  a  cleisto- 
gene  condition.  Thelymitra  longifolia  is  likewise  fer- 
tilised in  the  bud,  according  to  Mr.  Fitzgerald,  but 
the  flowers  open  for  about  an  hour  on  fine  days,  and 
thus  cross-fertilisation  is  at  least  possible.  On  the 
other  hand,  the  species  of  the  allied  genus  Diuris  are 
said  to  be  wholly  dependent  on  insects  for  their 
fertilisation. 

♦  '  Variation  of  Animals  and  Plants  under  Domestication,'  2nd  edit 
voL  ii.  p.  309. 


128  MALAXED.  Chap.  V 


CHAPTER  V. 

MALAXED   AND   EPIDENDRE^. 

Malaxis  paludosa— Masdevallia,  curious  closed  flowers — Bolbophyllmn, 
labellum  kept  in  constant  movement  by  every  breath  of  air — Dendro- 
bium,  contrivance  for  self-fertilisation — Cattleya,  simple  manner  of 
fertilisation — Epidendrum — Self-fertile  Epidendrese. 

1  HAVE  now  described  the  manner  of  fertilisation  of 
fifteen  genera,  found  in  Britain,  which  belong,  accord- 
ing to  Lindley's  classification,  to  the  Ophrese,  Arethu- 
seae,  and  Neottese.  A  brief  account  of  several  foreign 
genera  belonging  to  these  same  tribes  has  been  added, 
from  observations  published  since  the  appearance  of 
the  first  edition  of  this  book.  We  will  now  turn  to 
the  great  exotic  tribes  of  the  Malaxe?e,  Epidendrese, 
and  Vandese,  which  ornament  in  so  wonderful  a 
manner  the  tropical  forests.  My  chief  object  in 
examining  these  latter  forms  has  been  to  ascertain 
whether  their  flowers  were  as  a  general  rule  fertilised 
by  pollen  brought  by  insects  from  another  plant.  J 
also  wished  to  learn  whether  the  pollinia  underwent 
tliose  curious  movements  of  depression  by  which,  as 
I  had  discovered,  they  are  placed,  after  being  removed 
by  insects,  in  the  proper  position  for  striking  the 
stigmatic  surface. 

By  the  kindness  of  many  friends  and  strangers  T 
have  been  enabled  to  examine  fresh  flowers  of  several 
species,  belonging  to  at  least  fifty  exotic  genera,  in 
the  several  sub-tribes  of  the  above  three  great  tribes.* 

*  I  am  particularly  indebted  to  Dr.  Hooker,  who  on  every  orca- 


Chap.  V 


MALAXIS    PALUDOSA. 


129 


It  is  not  my  intention  to  describe  the  means  of  fertili- 
sation in  all  these  genera,  but  merely  to  select  a  few 
curious  cases  which  illustrate  the  foregoing  descrip- 
tions. The  diversity  of  the  contrivances  adapted  to 
favour  the  intercrossing  of  flowers,  seems  to  be  ex- 
haustless. 


MALAXED. 

Malaxis  paludosa. — This  rare  orchid  *  is  the  sole 
representative  of  the  tribe  in  this  country,  and  it  is 
the  smallest  of  all  the  British  species.  The  labellum 
is  turned  upwards,!  instead  of  downwards,  so  that  it 
does  not  afford  a  landing-place  for  insects  as  in  most 
other  Orchids.  Its  lower  margin  clasps  the  column, 
making  the  entrance  into  the  flower  tubular.     From 


sion  has  given  me  liis  invaluable 
advice,  and  has  never  become 
weary  of  sending  me  specimens 
from  the  Koyal  Gardens  at  Kew. 

Mr.  James  Veitch,  jun.,  has 
generously  given  me  many  biau- 
tiful  Orchids,  some  of  which  were 
of  especial  service.  Mr.  R.  Parker 
also  sent  me  an  extremely  valu- 
able series  of  forms.  Lady  Dorothy 
Nevill  most  kindly  placed  her 
magnificent  collection  of  Orchids 
at  my  disposal.  Mr.  Eucker  of 
West  Hill,  Wandsworth,  sent  me 
repeatedly  lar^e  spikes  of  Catase- 
tum.  a  Mormodes  of  extreme  value 
and  some  Dtndrobiums.  Mr. 
Ri;dgers  of  Sevenoaks  has  given 
me  interesting  inforruation.  Mr. 
Bateman,  so  well  known  for  his 
magnificent  work  on  Orchids, 
sent  me  a  number  of  interesting 
forms,  including  the  wcmderful 
Angripcum  sesquipedale.  I  am 
greatly  indebted  to  jMr.  Turnbull 
of  Down  for  allowing  me  the  free 
use  of  his  hothouses,  and  for 
giving  me  some  interesting  Or- 
chida  ;   and  to  his  gardener,  Mr. 

7 


Ilorwood,  for  his  aid  in  some  of 
my  observations. 

Professor  Oliver  has  kindly 
assisted  me  with  his  large  stores 
of  knowledge,  and  has  called  my 
attention  to  several  papers.  Lastly, 
Dr.  Lindley  has  sent  me  fresh 
and  dried  specimens,  and  has  in 
the  kindest  manner  helped  me  in 
various  ways. 

To  these  gentlemen  I  can  only 
express  my  corlial  thanks  for 
their  unweai'ied  and  generous 
kindness. 

*  I  am  greatly  indebted  to  Mr. 
Wallis,  of  Hartfield,  in  Sussex, 
for  numerous  living  specimens  of 
this  Orchid. 

t  Sir  James  Smith.  I  believe, 
first  noticed  this  fact  in  the 
'  English  Flora,'  vol.  iv.  p.  47, 
1828.  Towards  the  summit  of 
the  spike  the  lower  sepal  does  not 
depend,  as  represented  in  the 
woodcut  (fig.  19,  A),  but  projects 
nearly  at  right  angles.  Nor  are 
the  flowers  always  so  completely 
twisted  round  aa  licre  represented 


lig.  19, 


^--Aii^jJU^ 


MaLAXIS  PALUDOfiA. 

(Partly  copied  from  Bauer,  but  modified  from  living  specimens.) 


a.   anther.  v.    spiral  vessels. 

p.    pollen.  r.    rostellum. 

cl.  clinandrum.      s.    stigma. 
I.     label  lum. 

tt.  the  sepal  which  in  most  orchids 
stands  on  the  upper  side  of  the 
flower. 

k.  Perfect  flower  viewed  laterally, 
with  the  labellum  in  its  natu- 
ral position,  upwards. 

R,  Column  viewed  in  front,  showing 
the  rostellum,  the  pocket-like 
stigma,  and  the  anterior  late- 
ral portions  of  tne  clinandrum. 


C.  Back   view  of  the  column  in  a 

flower-bud,  showing  the  anther 
with  the  included  pear-shaped 
polliuia  dimly  seen,  and  the 
posterior  edges  of  the  clinan- 
drum. 

D.  Back  view  of  an  expanded  flower, 

with  the  anther  now  contracted 
and  shrivelled,  exposing  the 
pollinia. 

E.  The  two  pollinia  ati»ched  to  a 

little  transverse  mass  of  viscid 
matter,  hardened  by  spirits  of 
wine. 


Chap.  V.  MALAXIS   PALUDOSA.  131 

its  position  it  partially  protects  the  organs  of  fructi- 
fication (fig.  19).  In  most  of  the  Orcliidese,  the  upper 
sepal  and  the  two  upper  petals  afford  protection ;  but 
here  these  two  petals  and  all  the  sepals  are  reflexed 
(as  may  be  seen  in  the  drawing,  fig.  A),  apparently  to 
allow  insects  freely  to  visit  the  flower.  The  position 
of  the  labellum  is  the  more  remarkable,  because  it 
has  been  purposely  acquired,  as  shown  by  the  ovarium 
being  spirally  twisted.  In  all  Orchids  the  labellum 
is  properly  directed  upwards,  but  assumes  its  usual 
position  on  the  lower  side  of  the  flower  by  the  twist- 
ing of  the  ovarium ;  but  in  Malaxis  the  twisting  has 
been  carried  so  far  that  the  flower  occupies  the  posi- 
tion which  it  would  have  held  if  the  ovarium  had 
not  been  at  all  twisted,  and  which  the  ripe  ova- 
rium afterwards  assumes,  by  a  process  of  gradual 
untwisting. 

When  the  minute  flower  is  dissected,  the  column  is 
seen  to  be  longitudinally  tripartite;  the  middle 
portion  of  the  upper  half  (see  fig.  B)  is  the  rostellum. 
The  upper  edge  of  the  lower  part  of  the  column 
projects  where  united  to  the  base  of  the  rostellum, 
and  forms  a  rather  deep  fold.  This  fold  is  the  stig- 
matic  cavity,  and  may  be  compared  to  a  waistcoat- 
pocket.  I  found  pollen-masses  which  had  their  broad 
ends  pushed  by  insects  into  this  pocket ;  and  a 
bundle  of  pollen-tubes  had  here  penetrated  the 
stigmatic  tissue. 

The  rostellum,  which  stands  immediately  above  the 
stigmatic  cavity,  is  a  tallrmembranous  projection  of  a 
whitish  colour,  formed  of  square  cells,  and  is  covered 
with  a  thin  layer  of  viscid  matter  :  it  is  slightly  con- 
cave posteriorly,  and  its  crest  is  surmounted  by  a 
minute  tongue-shaped  mass  of  viscid  matter.  The 
column,  with  its  narrow  pocket-like  stigma  and  the 


132  MALAXED.  Chap.  V. 

rostellum  above,  is  united  on  each  side  behind  to  a 
'green  membranous  expansion,  convex  exteriorly  and 
concave  interiorly,  of  which  the  summits  on  each  side 
are  pointed  and  stand  a  little  above  the  crest  of  the 
rostellum.  These  two  membranes  sweep  round  (see 
back  views,  figs.  C  and  D),  and  are  united  to  the 
filament  or  base  of  the  anther ;.  they  thus  form  a  cup- 
like clinandrum  behind  the  rostellum.  The  use  of  this 
cup  is  to  protect  laterally  the  pollen-masses.  When 
I  have  to  treat  of  the  homologies  of  the  different  parts, 
it  will  be  shown  by  the  course  of  the  spiral  vessels 
that  these  two  membranes  consist  of  the  two  upper 
anthers  of  the  inner  whorl,  in  a  rudimentary  condition, 
but  utilised  for  this  special  purpose. 

In  a  flower  before  it  expands,  a  little  mass  or  drop 
of  viscid  fluid  may  be  seen  on  the  crest  of  the  ros- 
tellum, rather  overhanging  its  front  surface.  After 
the  flower  has  remained  open  for  a  little  time,  this 
drop  shrinks  and  becomes  more  viscid.  Its  chemical 
nature  is  difi'erent  from  that  of  the  viscid  matter  in 
most  Orchids,  for  it  remains  fluid  for  many  days, 
though  fully  exposed  to  the  air.  From  these  facts 
I  concluded  that  the  viscid  fluid  exuded  from  ^  the 
crest  of  the  rostellum;  but  fortunately  I  examined 
a  closely-allied  Indian  form,  namely,  the  Microstijlia 
rhedii  (sent  me  from  Kew  by  Dr.  Hooker),  and  in 
this,  before  the  flower  opened,  there  was  a  similar  drop 
of  viscid  matter  ;  but  on  opening  a  still  younger  bud, 
I  found  a  minute,  regular,  tongue-shaped  projection 
on  the  crest  of  the  rostellum,  formed  of  cells,  which 
when  slightly  disturbed  resolved  themselves  into  a 
drop  of  viscid  matter.  At  this  age,  also,  the  front 
surface  of  the  whole  rostellum,  between  its  crest  and 
the  pocket-like  stigma,  was  coated  with  cells  filled 
with  similar  brown  viscid  matter ;    so  that  there  can 


Chap.  V.  MALAXIS   PALUDOSA.  133 

be  little  doubt,  had  I  examined  a  young  enough  bud 
of  Malaxis,  I  should  have  found  a  similar  minute 
tongue-shaped  cellular  projection  on  the  crest  of  the 
rostellum. 

The  anther  opens  widely  whilst  the  flower  is  in 
bud,  and  then  shrivels  and  contracts  downwards,  so 
that,  when  the  flower  is  fully  expanded,  the  pollinia 
are  quite  naked,  with  the  exception  of  their  broad 
lower  ends,  w^hich  rest  in  two  little  cups  formed  by 
the  shrivelled  anther-cells.  This  contraction  of  the 
anther  is  represented  in  fig.  D  in  comparison  with  fig. 
C,  which  shows  the  state  of  the  anther  in  a  bud. 
The  upper  and  much  pointed  ends  of  the  pollinia 
rest  on,  but  project  beyond,  the  crest  of  the  rostellum; 
in  the  bud  they  are  unattached,  but  by  the  time  the 
flower  opens  they  are  always  caught  by  the  posterior 
surface  of  the  drop  of  viscid  matter,  of  which  the 
anterior  surface  projects  slightly  beyond  the  face  of 
the  rostellum.  That  they  are  caught  without  any 
mechanical  aid  I  ascertained  by  allowing  some  buds 
to  open  in  my  room.  In  fig.  E  the  pollinia  are  shown 
exactly  as  they  appeared  (but  not  quite  in  their 
natural  position)  when  removed  by  a  needle  from  a 
specimen  kept  in  spirits  of  wine,  in  which  the  irre- 
gular little  mass  of  viscid  matter  had  become  hardened 
and  adhered  firmly  to  their  tips. 

The  pollinia  consist  of  two  pairs  of  very  thin  leaves 
of  waxy  pollen ;  and  the  four  leaves  are  formed  of 
angular  compound  grains  which  never  separate.  As 
the  pollinia  are  almost  loose,  being  retained  merely  by 
the  adhesion  of  their  tips  to  the  viscid  fluid,  and  by 
their  bases  resting  in  the  shrivelled  anther-cells,  and 
as  the  petals  and  sepals  are  much  reflexed,  the  pollinia, 
when  the  flower  is  fully  expanded,  would  have  been 
liable  to  be  blown  away  or  out  of  their  proper  position, 


134  MALAXE.E.  CiiAP.  V, 

had  it  not  been  for  the  membranous  expansions  on 
each  side  of  the  column  forming  the  clinandrum, 
within  which  they  lie  safely. 

When  an  insect  inserts  its  proboscis  or  head  into 
the  narrow  space  between  the  upright  labellum  and 
the  rostellum,  it  will  infallibly  touch  the  little  pro- 
jecting viscid  mass,  and  as  soon  as  it  flies  away  it 
will  withdraw  the  pollinia.  I  easily  imitated  this 
action  by  inserting  any  small  object  into  the  tubular 
flower  between  the  labellam  and  rostellum.  When 
the  insect  visits  another  flower,  the  very  thin  pollen- 
leaves  attached  parallel  to  the  proboscis,  or  head,  will 
be  forced  into  the  pocket-like  stigma  with  their  broad 
ends  foremost.  I  found  pollinia  in  this  position  glued 
to  the  upper  membranous  expansion  of  the  rostellum, 
and  with  a  large  number  of  pollen-tubes  penetrating 
the  stigmatic  tissue.  The  use  of  the  thin  layer  of 
viscid  matter,  which  coats  the  surface  of  the  rostellum 
in  this  genus  and  in  Microstylis,  and  which  is  of  no 
use  for  the  transportal  of  the  pollen  from  flower  to 
flower,  seems  to  be  to  keep  the  leaves  of  pollen  fixed 
in  the  narrow  stigmatic  cavity  when  their  lower  ends 
have  been  inserted  by  insects.  This  fact  is  rather 
interesting  under  a  homological  point  of  view,  for,  as 
we  shall  hereafter  see,  the  primordial  nature  of  the 
viscid  matter  of  the  rostellum  is  that  which  is  common 
to  the  stigmatic  secretion  of  most  flowers,  namely,  the 
retention  of  the  pollen,  when  placed  by  any  means  on 
its  stigma. 

The  flowers  of  the  Malaxis,  though  so  small  and 
inconspicuous,  are  highly  attractive  to  insects.  This 
was  shown  by  the  pollinia  having  been  removed  from 
all  the  flowers  on  the  spikes  which  I  examined, 
excepting  from  one-  or  two  close  under  the  buds.  In 
some   old   flower-spikes   every   single   pollinium  had 


Chap.y.  pleueothallis  peolifera.  135 

been  carried  away.  Insects  sometimes  remove  only 
one  of  the  two  pairs.  I  noticed  a  flower  with  all  four 
pollen-leaves  still  in  place,  with  a  single  one  in  the 
stigmatic  cavity;  and  this  mnst  clearly  have  been 
brought  by  some  insect.  Within  the  stigmas  of  many 
other  flowers  pollen-leaves  were  observed.  The  plant 
produces  plenty  of  seed  ;  and  thirteen  of  the  twenty-one 
lower  flowers  on  one  spike  had  formed  large  capsules. 

We  will  now  turn  to  some  exotic  genera.  The  pol- 
linia  of  Fleurothallis  proUfera  and  ligidata  (?)  have  a 
minute  caudicle,  and  mechanical  aid  is  requisite  to 
force  the  viscid  matter  from  the  under  side  of  the 
rostellum  into  the  anther,  thus  to  catch  the  caudicles 
and  remove  the  pollinia.  On  the  other  hand,  in  our 
British  Malaxis  and  in  Microstijlis  rhedii  from  India, 
the  upper  surface  of  the  minute  tongue-shaped  ros- 
tellum becomes  viscid  and  adheres  to  the  pollinia 
without  any  mechanical  aid.  This  appears  likewise  to 
be  the  case  with  Stelis  racemiflora,  but  the  flowers  were 
not  in  a  good  state  for  examination.  I  mention  this 
latter  flower  partly  because  some  insect  in  the  hot- 
house at  Kew  had  removed  most  of  the  pollinia,  and 
had  left  some  of  them  adhering  to  the  lateral  stigmas. 
These  curious  little  flowers  are  widely  expanded  and 
much  exposed ;  but  after  a  time  the  three  sepals  close 
together  with  perfect  exactness,  so  that  it  is  scarcely 
possible  to  distinguish  an  old  flower  from  a  bud  :  yet, 
to  my  surprise,  the  closed  flowers  opened  when  im- 
mersed in  water. 

The  allied  Masdevallia  fenestrata  bears  an  extra- 
ordinary flower.  The  three  sepals  instead  of  closing, 
as  in  the  case  of  Stelis  after  the  flower  has  remained 
for  a  time  expanded,  cohere  togetlier  and  never  open. 
Two  minute,  lateral,  oval  windows  (hence  the  name 
fenestrata),  are  seated  high  up  the  flower  opposite  each 


136  MALAXE.E.  Chap.  V. 

other,  and  afford  the  only  entrance ;  but  the  presence 
of  these  two  minute  windows  (fig.  20)  shows  how  neces- 
sary it  is  that  insects  should  visit  the  flower  in  this 
case  as  in  that  of  most  other  Orchids.  How  insects 
perform  the  act  of  fertilisation  I  have  failed  to  under- 
stand. At  the  bottom  of  the  roomy  and  dark  chamber 
formed  by  the  closed  sepals,  the  minute  column  stands, 
and  in  front  of  it  is  the  furrowed  labellum,  with  a 
highly  flexible  hinge,  and  on  each  side  the  two  upper 
petals ;  a  little  tube  being  thus  formed.  When  there- 
p.    20  ^^^'®   ^  minute   insect   enters,  or 

^^.^^^^      which  is  less  probable,  a  larger  in- 
/^'^  '>  ^^'f^^  sect  inserts  its  proboscis  through 
'''<    ^        'tj        either  window,  it  has  to  find  by 
the  sense  of  touch  the  inner  tube 
i/  in  order  to  reach  the  nectary  at 

y  the  base  of  the  flower.     Within 

^^^/A — ^  the   little   tube,  formed   by   the 

Masdevallia  fenes-      column,    labellum,    and    lateral 
TRATA.  petals,  a  broad  and  hinged  rostel- 

The  window  on  the  near  side  inm    proi'ects    at    rifi^ht    auHes, 

IS  shown  darkly  shaded.  i  •    i  -n        i  ,  t 

which  can   easily   be    upturned. 

Its  under  surface  is  viscid,  and 
this  viscid  matter  soon  sets  hard  and  dry.  The  minute 
caudicles  of  the  pollinia,  projecting  out  of  the  anther- 
case,  rest  on  the  base  of  the  upper  membranous  surface 
of  the  rostellum.  The  stigmatic  cavity  when  mature 
is  not  very  deep.  After  cutting  away  the  sepals  I 
vainly  endeavoured,  by  pushing  a  bristle  into  the 
tubular  flower,  to  remove  the  pollinia,  but  by  the  aid 
of  a  bent  needle,  this  was  effected  without  much 
difficulty.  The  whole  structure  of  the  flower  seems 
as  if  intended  to  prevent  the  flower  from  being  easily 
fertilised ;  and  this  proves  that  we  do  not  understand 
its  structure.     Some  small  insect  had  entered  one  of 


Chap.  V.  BOLBOPHYLLUM.  137 

the  flowers  in  the  hothouse  at  Kew,  for  many  eggs 
were  deposited  within  it,  near  the  base. 

Of  Bolbophyllum  I  examined  the  curious  little 
flowers  of  four  species,  which  I  will  not  attempt  fully 
to  describe.  In  B.  cupreum  and  coeoinum,  the  upper  and 
lower  surfaces  of  the  rostellum  resolve  themselves  into 
viscid  matter,  which  has  to  be  forced  upwards  by  insects 
into  the  anther,  so  as  to  secure  the  pollinia.  I  effected 
this  easily  by  passing  a  needle  down  the  flower,  which 
is  rendered  tubular  by  the  position  of  the  labellum, 
and  then  withdrawing  it.  In  B.  rliizophorse  the  anther- 
case  moves  backwards,  when  the  flower  is  mature, 
leaving  the  two  pollen-masses  fully  exposed,  adhering 
to  the  upper  surface  of  the  rostellum.  They  are  held 
together  by  viscid  matter,  and,  judging  from  the 
action  of  a  bristle,  are  always  removed  together.  The 
stigmatic  chamber  is  very  deep  with  an  oval  orifice, 
which  exactly  fits  one  of  the  two  pollen-masses.  After 
the  flower  has  remained  open  for  some  time,  the  sides 
of  the  oval  orifice  close  in  and  shut  the  stigmatic 
chamber  completely, — a  fact  which  I  have  observed  in 
no  other  Orchid,  and  which,  I  presume,  is  here  related 
to  the  much  exposed  condition  of  the  whole  flower. 
When  the  two  pollinia  were  attached  to  a  needle  or 
bristle,  and  were  forced  against  the  stigmatic  chamber, 
one  of  the  two  glided  into  the  small  orifice  more  readily 
than  could  have  been  anticipated.  Nevertheless,  it  is 
evident  that  insects  must  place  themselves  on  suc- 
cessive visits  to  the  flowers  in  precisely  the  same 
position,  so  as  first  to  remove  the  two  pollinia,  and 
then  force  one  of  them  into  the  stigmatic  orifice.  The 
two  upper  filiform  petals  would  serve  as  guides  to 
the  insect ;  but  the  labellum,  instead  of  making  the 
flower  tubular,  hangs  down  just  like  a  tongue  out  of  a 
widely  open  mouth. 


138  MALAXED.  Chap.  V 

The  labelliim  in  all  the  species  which  I  have  seen, 
more  especially  in  B.  rhizopliorse,  is  remarkable  by 
being  joined  to  the  base  of  the  column  by  a  very 
narrow,  thin,  white  strap,  which  is  highly  elastic  and 
flexible ;  it  is  even  highly  elastic  when  stretched, 
like  an  india-rubber  band.  When  the  flowers  of  this 
species  were  blown  by  a  breath  of  wind  the  tongue-like 
labella  all  oscillated  to  and  fro  in  a  very  odd  manner. 
In  some  species  not  seen  by  me,  as  in  B,  harbigerum, 
the  labellum  is  furnished  with  a  beard  of  fine  hairs, 
and  these  are  said  to  cause  the  labellum  to  be  in 
almost  constant  motion  from  the  slightest  breath  of 
air.  What  the  use  can  be  of  this  extreme  flexibility 
and  liability  to  movement  in  the  labellum,  I  cannot 
conjecture,  unless  it  be  to  attract  the  notice  of  insects, 
as  the  flowers  of  these  species  are  dull-coloured,  small, 
and  inconspicuous,  instead  of  being  large,  brightly- 
coloured,  and  conspicuous  or  odoriferous,  as  in  so  many 
other  Orchids.  The  labella  of  some  of  the  species  are 
said  to  be  irritable,  but  I  could  not  detect  a  trace  of 
this  quality  in  those  examined  by  me.  According  to 
Lindley,  the  labellum  of  the  allied  Megadinium  falca- 
tum  spontaneously  oscillates  up  and  down. 

The  last  genus  of  the  Malaxea6  which  I  will  mention 
is  Dendrobium,  of  which  one  at  least  of  the  species, 
namely  D.  chrysanthum,  is  interesting,  from  being 
apparently  contrived  to  effect  its  own  fertilisation,  if 
an  insect,  when  visiting  the  flower,  should  fail  to 
remove  the  pollen-masses.  The  rostellum  has  an 
upper  and  a  small  lower  surface  composed  of  mem- 
brane; and  between  these  is  a  thick  mass  of  milky- 
white  matter  which  can  be  easily  forced  out.  This 
white  matter  is  less  viscid  than  is  usual ;  but  when 
exposed  to  the  air  a  film  forms  over  it  in  less  than 
half  a  minute,  and  it  soon  sets  into  a  waxy  or  cheesy 


Chap.  V. 


DENDKOBIUM   CHKYSANTHUM. 


139 


substance.  The  large  concave  but  shallow  stigmatic 
surface  is  seated  beneath  the  rostellum.  The  pro- 
duced anterior  lip  of  the  anther  (see  A)  almost  entirely 
covers  the  upper  surface  of  the  rostellum.     The  fila- 

Fig.  21. 


DlOTDROBIDM  CIIRYSANTHUM. 


anther.  s.    stigma. 

rostellum.         /.    labellum. 
n.  nectary. 

Lateral  view  of  flower,  with  the 
anther  in  its  proper  position, 
before  the,  ejection  of  the  pol- 
linia.  All  the  sepals  and  petals 
are  removed  except  the  label- 
lum, which  is  longitudinally 
bisected. 


B.  Outline  of  column,  viewed  later- 

ally, after  the  anther  has  ejected 
the  pollinia. 

C.  Front  view  of  column,  showing 

the  empty  cells  of  the  anther, 
after  it  has  ejected  its  pollinia. 
The  anther  is  represented  hang- 
ing too  low  down,  and  covering 
more  of  the  stigma  than  it 
really  does. 


ment  of  the  anther  is  of  considerable  length,  but  is 
hidden  in  the  side  view,  A,  behind  the  middle  of  the 
anther;  in  the  section,  B,  it  is  seen,  after  it  has 
sprung  forward  :  it  is  elastic,  and  presses  the  anther 
firmly  down  on   the   inclined   surface   of  the   clinan- 


140  MALAXED  Chap.  V 

drum  (see  fig.  B)  which  lies  behind  the  rostellum. 
When  the  flower  is  expanded  the  two  pollinia, 
united  into  a  single  mass,  lie  quite  loose  on  the 
clinandrum  and  under  the  anther-case.  The  labellum 
embraces  the  column,  leaving  a  passage  in  front.  The 
middle  portion  of  the  labellum  (as  may  be  seen  in 
fig.  A)  is  thickened,  and  extends  up  as  far  as  tlie 
top  of  the  stigma.  The  lowest  part  of  the  column 
is  developed  into  a  saucer-like  nectary,  which  secretes 
honey. 

As  an  insect  forces  its  way  into  one  of  these  flowers, 
the  labellum,  which  is  elastic,  will  yield,  and  the 
projecting  lip  of  the  anther  will  protect  the  rostellum 
from  being  disturbed ;  but  as  soon  as  the  insect 
retreats,  the  lip  of  the  anther  wdll  be  lifted  up,  and 
the  viscid  matter  from  the  rostellum  forced  into  the 
anther,  gluing  the  pollen-mass  to  the  insect,  which 
will  thus  be  transported  to  another  flower.  I  easily 
imitated  this  action ;  but  as  the  pollen-masses  have 
no  caudicle  and  lie  rather  far  back  within  the  clinan- 
drum beneath  the  anther,  and  as  the  matter  from  the 
rostellum  is  not  highly  viscid,  they  were  sometimes 
left  behind. 

Owing  to  the  inclination  of  the  base  of  the  clinan- 
drum, and  owing  to  the  length  and  elasticity  of  the 
filament,  as  soon  as  the  anther  is  lifted  up  it  always 
springs  forward,  over  the  rostellum,  and  remains 
hanging  there  with  its  lower  empty  surface  (fig.  C)  sus- 
pended over  the  summit  of  the  stigma.  The  filament 
now  stretches  across  the  space  (see  fig.  B)  which 
was  originally  covered  by  the  anther.  Several  times, 
having  cut  off  all  the  petals  and  labellum,  and  laid 
the  flower  under  the  microscope,  I  raised  the  lip  of  the 
anther  with  a  needle,  without  disturbing  the  rostellum, 
and  saw  the  anther  assume,  with  a  spring,  the  position 


Chap.  V.  DENDROBIUM   CHRYSANTIIUM.  141 

represented  sideways  in  fig.  B,  and  frontways  in  fig. 
C.  By  this  springing  action  the  anther  scoops  the 
pollinium  out  of  the  concave  clinandrum,  and  pitches 
it  up  in  the  air,  with  exactly  the  right  force  so  as  to 
fall  down  on  the  middle  of  the  viscid  stigma,  where  it 
adheres. 

Under  nature,  however,  the  action  cannot  be  as  thus 
described,  for  the  labellum  hangs  downwards ;  and  to 
understand  what  follows,  the  drawing  should  be  placed 
in  an  almost  reversed  position.  If  an  insect  failed  to 
remove  the  pollinium  by  means  of  the  viscid  matter 
from  the  rostellum,  the  pollinium  would  first  be  jerked 
downwards  on  to  the  protuberant  surface  of  the  label- 
lum, placed  immediately  beneath  the  stigma.  But  it 
must  be  remembered  that  the  labellum  is  elastic,  and 
that  at  the  same  instant  that  the  insect,  in  the  act  of 
leaving  the  flower,  lifts  up  the  lip  of  the  anther,  and 
so  causes  the  pollinium  to  be  shot  out,  the  labellum 
will  rebound  back,  and  striking  the  pollinium  will 
pitch  it  upwards,  so  as  to  hit  the  adhesive  stigma. 
Twice  I  succeeded  in  effecting  this  by  imitating  the 
retreat  of  an  insect,  with  the  flower  held  in  its  natural 
position ;  and  on  opening  it,  found  the  pollinium 
glued  to  the  stigma. 

This  view  of  the  use  of  the  elastic  filament,  seeinof 
how  complicated  the  action  must  be,  may  appear 
fanciful ;  but  we  have  seen  so  many  and  such  curious 
adaptations,  that  I  cannot  believe  the  strong  elasticity 
of  the  filament  and  the  thickening  of  the  middle  part 
of  the  labellum  to  be  useless  points  of  structure.  If 
tlie  action  be  as  I  have  described,  we  can  perceive 
their  meaning,  for  it  would  be  an  advantage  to  the 
plant  that  its  single  large  pollen-mass  should  not  be 
wasted,  supposing  that  it  failed  to  adhere  to  an  insect 
by  means  of  the  viscid  matter  from   the  rostellum. 


142  EPIDENDKE^.  Chap.  V. 

This  (iontrivance  is  not  common  to  all  the  species  of 
the  genus ;  for  in  neither  D.  higihhum  nor  D.  formosum 
was  the  filament  of  the  anther  elastic,  nor  was  the 
middle  line  of  the  labellum  thickened.  In  B.  tortile 
the  filament  is  elastic;  but  as  I  examined  only  a 
sinsrle  flower,  and  before  I  had  made  out  the  structure 
of  D.  chrijsantlium,  I  cannot  say  how  it  acts. 

Mr.  Anderson  states  *  that  on  one  occasion  the  flowers 
of  his  Dendrohium  cretaceum  did  not  expand,  and  yet 
they  produced  capsules,  one  of  which  he  sent  me. 
Almost  all  the  numerous  seeds  in  this  capsule  con- 
tained embryos,  thus  differing  greatly  from  the  cases 
presently  to  be  given  of  the  self-fertilised  seeds  from 
the  non-expanded  flowers  of  a  Cattleya.  Mr.  Anderson 
remarks  that  Dendrobiums  are  the  sole  representatives 
of  the  Malaxese  which,  as  far  as  he  has  seen,  spon- 
taneously form  capsules.  He  likewise  states  that  in 
the  immense  group  of  the  Vandese,  hereafter  to  be 
described,  none  of  the  species  under  his  care,  with 
the  exception  of  some  belonging  to  the  sub-division 
of  the  BrassidsB  and  of  Sarcanthus  farisliiiy  has  ever 
spontaneously  produced  a  capsule. 

EPIDENDKE^. 

The  Epidendrese  and  Malaxese  are  characterised  by 
the  pollen-grains  cohering  into  large  waxy  masses. 
In  the  latter  of  these  groups  the  pollinia  are  said  not 
to  be  furnished  with  caudicles,  but  this  is  not  uni- 
versally the  case,  for  they  exist  in  MasdevalUa  fenes- 
trata  and  some  other  species  in  an  efficient  condition, 
although  unattached  and  of  minute  size.  In  the 
Epidendreai,  on  the  other  hand,  free  or  unattached 
caudicles  are  elways  present.     For  my  purpose  these 

*    '  Journal  v.i  Horticulture,'  1S63,  pp.  20G,  287. 


Chap.  V.  CATTLEYA.  143 

two  great  tribes  might  have  been  run  together ;  as  the 
distinction  drawn  from  the  presence  of  caudicles  does 
not  always  hold  good.  But  difficulties  of  this  nature 
are  frequently  encountered  in  the  classification  of 
largely  developed  or  so-called  natural  groups,  in  which 
there  has  been  comparatively  little  extinction. 

I  will  begin  with  the  genus  Cattleya,  of  which  I 
have  examined  several  species.  These  are  fertilised 
in  a  very  simple  manner,  different  from  that  in  any 
British  Orchid.  The  rostellum  (r,  fig.  22,  A,  B)  is  a 
broad,  tongue-shaped  projection,  which  arches  slightly 
over  the  stigma ;  the  upper  surface  is  formed  of  smooth 
membrane ;  the  lower  surface  together  with  the  central 
portion  (originally  a  mass  of  cells)  consists  of  a  very 
thick  layer  of  viscid  matter.  This  viscid  mass  is 
hardly  separated  from  the  viscid  matter  thickly  coating 
the  stigmatic  surface  which  lies  close  beneath  the  ros- 
tellum. The  projecting  upper  lip  of  the  anther  rests 
on,  and  opens  close  over  the  base  of  the  upper  mem- 
branous surface  of  the  tongue-shaped  rostellum.  The 
anther  is  kept  closed  by  a  spring,  at  its  point  of  at- 
tachment on  the  top  of  the  column.  The  poUinia 
consist  of  four  (or  eight  in  Cattleya  crispa)  waxy 
masses,  each  furnished  (see  figs.  C  and  D)  with  a 
ribbon-like  tail,  formed  of  a  bundle  of  highly  elastic 
threads,  to  which  numerous  separate  pollen-grains  are 
attached.  The  pollen  therefore  consists  of  two  kinds, 
namely,  waxy  masses  and  separate  though  compound 
grains  (each,  as  usual,  consisting  of  four)  united  by 
elastic  threads.  This  latter  kind  of  pollen  is  identical 
with  that  of  Epipactis  and  other  Neottea3.*  These  tails, 
with  their  appended  pollen-grains,  act  as   caudicles, 

*  The  polK-n-masses  of  Bh  tia       published  by  Lindley  in  his  •  II- 
are   admirably  represented   on  a       lustrations.' 
large  scale  in  Hauer's  drawings, 


144 


EPIDENDKE^. 


Chap.  V. 


and  are  thus  designated,  for  they  serve  as  the  means 
for  the  removal  of  the  larger  waxy  masses  from  the 
anther-cells.  The  tips  of  the  caudicles  are  generally 
reflexed,  and  in  the  mature  flower  protrude  a  little 


Fig. 


CArrLEYA. 

a. 
b. 

P- 
r. 

anther. 

spring  at  the  top  of  the  column. 

pollen-masses. 

rostellum. 

B.  { 

s. 
col 

I. 

stigma, 
column, 
labellum. 

C.  1 

g- 

A. 

nectary. 

ovarium,  or  germen. 
Front  view  of  column,  with  all 
the  sepals  and  petals  removed. 

D.  . 

Section  and  lateral  view  of  th(3 
flower,  with  all  the  sepals  and 
petals  removed,  except  the  bi- 
sected labellum  shown  only  in 
outline. 
C.  Anther  viewed  on  the  under  side, 
showing  the  four  caudicles  with 
the  four  pollen-masses  beneath. 

A  single  pollinium,  viewed  later- 
ally, showing  the  pollen-mass 
and  caudicle. 


way  out  of  the  anther-case  (see  fig.  A)  lying  on  the 
base  of  the  upper  membranous  lip  of  the  rostellum. 
The  labellum  enfolds  the  column,  making  the  flower 


Chap.  V.  CATTLE  Y A.  145 

tubular,  and  its  lower  part  is  produced  into  a  nectary, 
which  penetrates  the  ovarium. 

Kow'  for  the  action  of  these  parts.  If  any  body  of 
size  proportional  to  that  of  the  tubular  flower  be 
forced  into  it — a  dead  humble-bee  acts  very  well — the 
tongue-shaped  rostellum  is  depressed,  and  the  object 
often  gets  slightly  smeared  with  viscid  matter ;  but 
in  withdrawing  it,  the  rostellum  is  upturned,  and  a 
surprising  quantity  of  viscid  matter  is  forced  over  the 
edges  and  sides,  and  at  the  same  time  into  the  lip  of 
the  anther,  which  is  also  slightly  raised  by  the  up- 
turning of  the  rostellum.  Thus  the  protruding  tips 
of  the  caudicles  are  instantly  glued  to  the  retreating 
object,  and  the  pollinia  are  withdrawn.  This  hardly 
ever  failed  to  occur  in  my  repeated  trials.  A  living 
bee  or  other  large  insect  alighting  on  the  fringed 
edge  of  the  labellum,  and  scrambling  into  the  flower, 
would  depress  the  labellum  and  would  be  less  likely 
to  disturb  the  rostellum,  until  it  had  sucked  the 
nectar  and  began  to  retreat.  When  a  dead  bee,  with 
the  four  waxy  balls  of  pollen  dangling  by  their 
caudicles  from  its  back,  is  forced  into  another  flower, 
some  or  all  of  them  are  caught  with  certainty  by  the 
broad,  shallow,  and  highly  viscid  stigmatic  surface, 
which  likewise  tears  off  the  grains  of  pollen  from  the 
threads  of  the  caudicles. 

That  living  humble-bees  can  thus  remove  the 
pollinia  is  certain.  Sir  W.  C.  Trevelyan  sent  to  Yir. 
Smith  of  the  British  Museum  a  Bomhns  liortorum, 
which  was  forwarded  to  me — caught  in  his  hothouse, 
where  a  Cattleya  was  in  flower— with  its  whole  bade, 
between  the  wings,  smeared  with  dried  viscid  matter, 
and  with  the  four  pollinia  attached  to  it  by  their 
caudicles,  ready  to  be  caught  by  the  stigma  of  any 
other  flower  if  the  bee  had  entered  one. 


146  EriDENDREiE.  Chap.  V 

Those  species  which  I  have  examined  of  Laelia, 
Leptotcs,  Sophronitis,  Barkeria,  Phaius,  Evelyna, 
Bletia,  Chysis,  and  Coelogyne,  resemble  Cattleya  in 
the  caudicles  of  the  pollinia  being  free,  and  in  the 
viscid  matter  from  the  rostellum  not  coming  into 
contact  with  them  without  mechanical  aid,  as  well  as 
in  their  general  manner  of  fertilisation.  In  Coelogyne 
crisfata  the  upper  lip  of  the  rostellum  is  much  elon- 
gated. In  Evehjna  carivata  and  Chysis  eight  balls  of 
waxy  pollen  are  all  united  to  a  single  caudicle.  In 
Barkeria  the  labellum,  instead  of  enfolding  the  column, 
is  pressed  against  it,  and  this  would  effectually  compel 
insects  to  brush  against  the  rostellum.  In  Epidendrum 
we  have  a  slight  difference ;  for  the  uj)per  surface  of 
the  rostellum,  instead  of  permanently  remaining  mem- 
branous, as  in  the  above-named  genera,  is  so  tender 
that  by  a  touch  it  breaks  up,  together  with  the  whole 
lower  surface,  into  a  mass  of  viscid  matter.  In  tliis 
case  the  whole  of  the  rostellum,  together  with  the 
adherent  pollinia,  must  be  removed  by  insects  as  they 
retreat  from  the  flower.  I  observed  in  E.  glaucum  that 
viscid  matter  exuded  from  the  upper  surface  of  the 
rostellum  when  touched,  as  happens  with  Epipactis. 
In  fact  it  is  difficult  to  say,  in  these  cases,  whether 
the  upper  surface  of  the  rostellum  should  be  called 
membrane  or  viscid  matter.  With  Chysis  this  matter 
sets  nearly  hard  and  dry  in  twenty  minutes,  and 
quite  so  in  thirty  minutes  after  its  removal  from  the 
rostellum. 

In  Epidendrum  floribundum  there  is  a  rather  greater 
difference :  the  anterior  horns  of  the  clinandrum  (i.  e. 
the  cup  on  the  summit  of  the  column  in  which  the 
pollinia  lie)  approach  each  other  so  closely  as  to 
adhere  to  the  two  sides  of  the  rostellum,  which  con- 
sequently lies  in  a  nick,  with  the  pollinia  seated  over 


Chap  V.  CATTLEYA.  147 

it ;  and  as,  in  this  species,  the  upper  surface  of  the 
rostellum  resolves  itself  into  yiscid  matter,  the  cau- 
dicles  of  the  pollinia  become  glued  to  it  without  any 
mechanical  aid.  The  pollinia,  though  thus  attached, 
cannot,  of  course,  be  removed  from  their  anther-cells 
without  the  aid  of  insects.  In  this  species  it  seems 
possible  (though,  from  the  position  of  parts,  not 
probable)  that  an  insect  might  drag  the  pollinia  out 
and  leave  them  on  the  stigma  of  the  same  flower.  In 
all  the  other  species  of  Epidendrum  which  I  examined, 
and  in  all  the  above-mentioned  genera,  it  is  evident 
that  the  viscid  matter  has  to  be  forced  upwards  into 
the  lip  of  the  anther  by  a  retreating  insect,  which 
would  thus  necessarily  carry  the  pollinia  from  one 
flower  to  the  stigma  of  another. 

Nevertheless,  self-fertilisation  takes  place  in  some 
Epidendreae.  Dr.  Criiger  says*  that  "we  have  in 
Trinidad  three  plants  belonging  to  this  family  (a 
Schomburgkia,  Cattleya,  and  Epidendron)  which  rarely 
open  their  flowers,  and  they  are  invariably  found  to  be 
impregnated  when  they  do  open  them.  In  these  cases 
it  is  easily  seen  that  the  pollen-masses  have  been  acted 
on  by  the  stigmatic  fluid,  and  that  the  pollen-tubes 
descend  from  the  pollen-masses  in  situ  down  into  the 
ovarian  canal."  Mr.  Anderson,  a  skilful  cultivator  of 
Orchids  in  Scotland,  also  states  that  several  of  his 
Epidendreae  fertilise  themselves  spontaneously.f  In 
the  case  of  Cattleya  crispa,  the  flowers  sometimes  do 
not  expand  properly ;  nevertheless  they  produce  cap- 
sules, one  of  which  he  sent  to  me.  It  contained  an 
abundance  of  seeds,  but  on  examination  I  found  that 


..*  ' '^^'^^^'  Linn.  Soc.  Bot.'  vol.  paper  Mr.  Gosse  gives  an  account 

viii.  1864,  p.  131.  of  his  microscopical  examination 

t    'Journal    of    Horticulture,'  of  the  self- fertilised  seeds. 
1863,  p.  206  and  287 :  in  the  latter 


148  EPIDENDEEJ2.  Chap.  V. 

only  about  one  per  cent,  contained  an  embryo.  Similar 
seeds  were  more  carefully  examined  by  Mr.  Gosse,  who 
found  that  two  per  cent,  contained  an  embryo.  About 
twenty-five  per  cent,  of  the  seeds  from  a  self-fertilised 
capsule  of  L^lia  cinnabarina,  also  sent  to  me  by 
Mr.  Anderson,  were  found  to  be  good.  It  is  therefore 
doubtful  whether  the  capsules  spontaneously  self-ferti- 
lised in  the  West  Indies,  as  described  by  Dr.  Cruger, 
were  fully  and  properly  fertilised.  Fritz  Miiller  in- 
forms me  that  he  has  discovered  in  South  Brazil 
an  Epidendrum  which  bears  three  pollen-producing 
anthers,  and  this  is  a  great  anomaly  in  the  order. 
This  species  is  very  imperfectly  fertilised  by  insects  ; 
but  by  means  of  the  two  lateral  anthers  the  flowers 
are  regularly  self-fertilised.  Fritz  Miiller  assigns  good 
reasons  for  his  belief  that  the  appearance  of  the  two 
additional  anthers  in  this  Epidendrum,  is  a  case  of 
reversion  to  the  primitive  condition  of  the  whole 
group.* 

♦  See  also  '  Bot.  Zeitnng,'  1869,  p.  226,  and  1870,  p.  152. 


Chap.  VI.  STRUCTURE   OF  COLUMIf.  149 


CHAPTEE  YI. 


VANDE^. 


Structure  of  the  columu  and  pollinia — Importance  of  the  elasticity  of 
the  pedicel;  its  power  of  movement — Elasticity  and  strength  of  the 
caudicles — Calanthe  with  lateral  stigmas,  manner  of  fertilisation — 
Angrsecum  sesquipedale,  wonderful  length  of  nectary — Species  with 
the  entrance  into  the  stigmatic  chamber  much  contracted,  so  that 
the  pollen-masses  can  hardly  be  inserted— Coryanthes,  extraordinary 
manner  of  fertilisation. 

We  now  come  to  the  immense  tribe  of  the  Yandese, 
which  includes  many  of  the  most  magnificent  produc- 
tions of  our  hothouses,  but  like  the  Epidendrese  has 
no  British  representative.  I  have  examined  twenty- 
nine  genera.  The  pollen  consists  of  waxy  masses,  as 
in  the  two  last  tribes,  and  each  ball  of  pollen  is 
furnished  with  a  caudicle,  which  becomes,  at  an  early 
period  of  growth,  united  to  the  rostellum.  The  cau- 
dicle is  seldom  attached  directly  to  the  viscid  disc,  as 
in  most  of  the  Ophrese,  but  to  the  upper  and  posterior 
surface  of  the  rostellum  ;  and  this  part  is  removed  by 
insects,  together  with  the  disc  and  pollen-masses.  The 
sectional  diagram  (fig.  23),  with  the  parts  separated, 
will  best  explain  the  type-structure  of  the  Yandese. 
As  in  the  rest  of  the  Orchidese  there  are  three  con- 
fluent pistils;  of  these  the  dorsal  one  (2)  forms  the 
rostellum  arching  over  the  two  others  (3)  which  unite 
to  form  a  single  stigma.  On  the  left  hand  we  have 
the  filament  (1)  bearing  the  anther.  The  anther  opens 
at  an  early  period,  and  the  tips  of  the  two  caudicles 
(but   only  one  caudicle  and  one  pollen-mass  are  re- 


150 


YANDEX. 


Chap.  VL 


presented  in  the  diagram)  protrude  in  a  not  fully- 
hardened  condition  through  a  small  slit,  and  adhere  to 
the  back  of  the  rostellum.  The  upper  surface  of  the 
rostellum  is  generally  hollowed  out  for  the  reception 
of  the  pollen-masses ;  it  is  represented  as  smooth  in 
the  diagram,  but  is  really  often  furnished  with  crests 


Fig.  23. 
anther.       caudicle 


,.-  pedicel  of 
rostellum. 


12     3 

Imaginary  Section,  illustrative  of  the  structure  of  the  column  in  the 

VANDKiE. 


(I.)  The  filament,  bearing  the  an- 
ther with  its  pollen-masses  ; 
the  anther  is  represented  after 
it  has  opened  along  its  whole 
under  surface,  so  that  the 
section  shows  only  the  dorsal 
surface. 


(2.)    The    upper    pistil,    with    the 

upper  part  moditied  mto  the 

rostellum. 
(3.)  The  two  lower  confluent  pistils, 

bearing    the    two    conflueut 

stigmas. 


or  knobs  for  the  attachment  of  the  two  caudicles. 
The  anther  afterwards  opens  more  widely  along  its 
under  surface,  and  leaves  the  two  pollen-masses  un- 
attached, excepting  by  their  caudicles  to  the  rostellum. 
During  an  early  period  of  growth,  a  remarkable 
change  has  been  going  on  in  the  rostellum :  either  its 
extremity  or  its  lower  surface  becomes  excessively 
viscid  (forming  the  viscid  disc),  and  a  line  of  separa- 


Chap.  TI.  STRUCTURE    OF   COLUMN.  151 

tion,  at  first  appearing  as  a  zone  of  hyaline  tissue,  is 
gradually  formed,  which  sets  free  the  disc,  as  well  as 
the  whole  upper  surface  of  the  rostellum,  as  far  back 
as  the  point  of  attachment  of  the  caudicles.  If  any 
object  now  touches  the  viscid  disc,  it,  together  with 
the  whole  back  of  the  rostellum,  the  caudicles  and 
pollen-masses,  can  all  be  readily  removed  together. 
In  botanical  works  the  whole  structure  between  the 
disc  or  viscid  surface  (generally  called  the  gland)  and 
the  balls  of  pollen  is  designated  as  the  caudicle ;  but 
as  these  parts  play  an  essential  part  in  the  fertilisation 
of  the  flower,  and  as  they  are  fundamentally  different 
in  their  origin  and  in  their  minute  structure,  I  shall 
call  the  two  elastic  ropes,  which  are  developed  strictly 
within  the  anther-cells,  the  caudicles  ;  and  the  portion 
of  the  rostellum  to  which  the  caudicles  are  attached 
(see  diagram),  and  which  is  not  viscid,  the  pedicel. 
The  viscid  portion  of  the  rostellum  I  shall  call,  as 
heretofore,  the  viscid  surface  or  disc.  The  whole  may 
be  conveniently  spoken  of  as  the  poUinium. 

In  the  Ophrese  we  have  (except  in  0.  pyramidalis 
and  a  few  other  species)  two  separate  viscid  discs.  In 
the  Yandeoe,  with  the  exception  of  Angra^cum,  we  have 
only  one  disc.  The  disc  is  naked,  or  is  not  enclosed 
in  a  pouch.  In  Habenaria  the  discs,  as  we  have  seen, 
are  separated  from  the  two  caudicles  by  short  drum- 
like pedicels,  answering  to  the  single  and  generally 
much  more  largely  developed  pedicel  in  the  Yandeae. 
In  the  Ophreae  the  caudicles  of  the  pollinia,  though 
elastic,  are  rigid,  and  serve  to  place  the  packets  of 
pollen  at  the  right  distance  from  the  insect's  head  or 
proboscis,  so  as  to  reach  the  stigma.  In  the  Yandea) 
this  end  is  gained  by  the  pedicol  of  the  rostellum. 
The  two  caudicles  in  the  Yandese  are  embedded  and 
attached   within   a  deep   cleft   in  the   pollen-masses. 


152  VANDE^.  Chap.  VI 

and  until  stretched  are  rarely  visible,  for  the  pollen- 
masses  lie  close  to  the  pedicel  of  the  rostellum.  These 
caudicles  answer  both  in  position  and  function  to  the 
elastic  threads,  by  which  the  packets  of  pollen  are  tied 
together  in  the  Ophreae,  at  the  point  where  they  become 
confluent ;  for  the  function  of  the  true  caudicle  in  the 
Vandeae  is  to  break  when  the  masses  of  pollen,  trans- 
ported by  insects,  adhere  to  the  stigmatic  surface. 

In  many  Vandeae  the  caudicles  are  easily  ruptured, 
and  the  fertilisation  of  the  flower,  as  far  as  this  point 
is  concerned,  is  a  simple  affair  ;  but  in  other  cases  their 
strength,  and  the  length  to  which  they  can  be  stretched 
before  they  break,  are  surprising.  I  was  at  first  per- 
plexed to  understand  what  purpose  these  qualities 
could  serve.  The  explanation  probably  is  that  the 
pollen-masses  in  this  tribe  are  very  precious  objects ; 
in  most  of  the  genera  a  flower  produces  only  two,  and 
judging  from  the  size  of  the  stigma  both  are  generally 
left  adhering  to  it.  In  other  genera,  however,  the 
orifice  leading  into  the  stigma  is  so  small  that  probably 
only  one  pollen-mass  is  left  on  it,  and  in  this  case  the 
pollen  from  one  flower  would  suffice  to  fertilise  two 
flowers,  but  never  a  greater  number.  From  the  large 
size  of  the  flowers  of  many  of  the  Vandeae,  they  no 
doubt  are  fertilised  by  large  insects,  and  these  whilst 
flying  about  would  be  likely  to  brush  away  and  lose 
the  pollinia  attached  to  them,  unless  the  caudicles  were 
very  strong  and  highly  elastic.  So  again,  when  an 
insect  thus  provided  visited  a  flower  either  too  young, 
with  its  stigma  not  yet  sufficiently  adhesive,  or  one 
already  impregnated,  with  its  stigma  beginning  to  dry, 
the  strength  of  the  caudicle  would  prevent  the  pollen- 
masses  from  being  uselessly  removed  and  lost. 

Although  the  stigmatic  surface  is  astonishingly 
adhesive  at  the  proper  period  in  many  of  these  Orchids, 


Chap.  VI.  SHAPE   OF  THE   POLLINIA.  153 

for  instance,  in  Phalaenopsis  and  Saccolabium,  yet  when 
I  inserted  their  pollinia  attached  to  a  rough  object  into 
the  stigmatic  chamber,  they  did  not  adhere  with  suffi- 
cient force  to  prevent  their  removal  from  the  object.  I 
even  left  them  for  some  little  time  in  contact  with  the 
adhesive  surface,  as  an  insect  would  do  whilst  feeding ; 
but  when  I  pulled  the  pollinia  straight  out  of  the 
stigmatic  chamber,  the  caudicles,  though  they  were 
stretched  to  a  great  length,  did  not  rupture,  nor  did 
their  attachment  to  the  object  yield  so  that  the  balls 
of  pollen  were  withdrawn.  It  then  occurred  to  me 
that  an  insect  in  flying  away  would  not  pull  the 
pollinia  straight  out  of  the  chamber,  but  would  pull 
at  nearly  right  angles  to  its  orifice.  Accordingly  I 
imitated  the  action  of  a  retreating  insect,  and  dragged 
the  pollinia  out  of  the  stigmatic  chamber  at  right 
angles  to  its  orifice;  and  now  the  friction  on  the 
caudicles  thus  caused,  together  with  the  adhesiveness 
of  the  stigmatic  surface,  generally  sufficed  to  rupture 
them;  the  pollen-masses  being  left  on  the  stigma. 
Thus,  it  seems  that  the  great  strength  and  extensi- 
bility of  the  caudicles,  which,  until  stretched,  lie  em- 
bedded within  the  pollen-masses,  serve  to  protect  the 
pollen-masses  from  being  accidentally  lost  by  an  insect 
whilst  flying  about,  and  yet,  by  friction  being  brought 
into  play,  allow  them  at  the  proper  time,  to  be  left 
adhering  to  the  stigmatic  surface ;  the  fertilisation  of 
the  flower  being  thus  safely  effected. 

The  discs  and  pedicels  of  the  pollinia  present  great 
diversities  in  shape,  and  an  apparently  exhaustless 
number  of  adaptations.  Even  in  species  of  the  same 
genus,  as  in  Oncidium,  these  parts  differ  greatly.  I 
here  give  a  few  figures  (fig.  24),  taken  almost  at  hazard, 
The  pedicel  generally  consists,  as  far  as  I  have  seen, 
of  a  thin  ribbon-shaped  membrane  (fig.  A) ;  sometimes 
8 


154 


VANDE.'R. 


Chap.  Y1. 


it  is  almost  cylindrical  (fig.  C)  but  often  of  the  moat 
diversified  shapes.  The  pedicel  is  generally  nearly 
straight,  but  in  Miltonia  dowesii  it  is  naturally  curved  ; 
and  in  some  cases,  as  we  shall  immediately  see,  it 
assumes,  after  removal,  various  shapes.  The  extensible 
and  elastic  caudicles,  by  which  the  pollen-masses  are 
attached  to  the  pedicel,  are  barely  or  not  at  all  visible, 
being  embedded  in  a  cleft  or  hollow  within  each 
pollen-mass.  The  disc,  which  is  viscid  on  the  under 
side,  consists  of  a  piece  of  thin  or  thick  membrane  of 

Fig.  2k 


POLLINIA    OF    VaNDE^. 


B.  Pollinium    ot    Brassia   maculata 
(copied  from  Bauer). 

C.  Pollinium  of  Stanhopea  saccata 
after  depression. 

D.  Pollinium  of  Sarcanthus  tereti- 
folius  after  depression. 


d.      viscid  disc 

ped.  pedicel. 

«.       pollen-masses. 

Tbe  caudicles,  being  embedded  within 

the  pollen-masses,  are  not  shown. 
A.  Pollinium    of    Oncidinm  grande 

after  partial  depression.  | 

varied  forms.  In  Acropera  it  is  like  a  pointed  cap ; 
in  some  cases  it  is  tongue-shaped,  or  heart-shaped 
(fig.  C),  or  saddle-shaped,  as  in  some  Maxillarias,  or 
like  a  thick  cushion  (fig.  A),  as  in  many  species  of 
Oncidium,  with  the  pedicel  attached  at  one  end,  instead 
of,  as  is  more  usual,  nearly  to  the  centre.  In  Angrsecum 
distichum  and  sesquipedale  the  rostellum  is  notched, 
and  two  separate,  thin,  membranous  discs  can  be 
removed,  each  carrying  by  a  short  pedicel  a  pollen- 
mass.     In  Sarcanthus  teretif alius  tlie  disc   (fig.  D)  is 


Chap.  VI.  MOVEMENTS   OF   THE   POLLINIA.  155 

very  oddly  shaped;  and  as  the  stigmatic  chamber 
is  deep  and  likewise  curiously  shaped,  we  are  led  to 
believe  that  the  disc  is  fastened  with  great  precision 
to  the  square  projecting  head  of  some  insect.* 

In  most  cases  there  is  a  plain  relation  between  the 
length  of  the  pedicel  and  the  depth  of  the  stigmatic 
chamber,  into  which  the  pollen-masses  have  to  be 
inserted.  In  some  few  cases,  however,  in  which  a  long 
pedicel  and  a  shallow  stigma  co-exist,  we  shall  presently 
meet  with  curious  compensating  actions.  After  the 
disc  and  pedicel  have  been  removed,  the  shape  of  the 
remaining  part  of  the  rostellum  is  of  course  altered, 
being  now  slightly  shorter  and  thinner,  and  sometimes 
notched.  In  Stanhopea,  the  entire  circumference  of 
the  extremity  of  the  rostellum  is  removed,  and  a  thin, 
pointed,  needle-like  process  alone  is  left,  which  origin- 
ally ran  up  the  centre  of  the  disc. 

If  we  now  turn  to  the  diagram  (fig.  23,  p.  150),  and 
suppose  the  rectangularly  bent  rostellum  to  be  thinner 
and  the  stigma  to  lie  closer  beneath  it  than  is  there 
represented,  we  shall  see  that,  if  an  insect  with  a  poUi- 
nium  attached  to  its  head  were  to  fly  to  another  flower 
and  occupy  exactly  the  same  position  which  it  held 
whilst  the  attachment  was  effected,  the  pollen-masses 
would  be  in  the  right  position  for  striking  the  stigma, 
especially  if,  from  their  weight,-  they  were  to  become 
in  the  least  degree  depressed.  This  is  all  that  takes 
place  in  Ly caste  sJcinnerii,  Gymhidium  giganteum, 
Zygopetalum  mackai,  Angrwcum  ebarneu77i,  Miltonia 
dowesii,  in  a  Warrea,  and,  I  believe,  in  Galeandra 
funJcii.     But  if  in  our  diagram  we  suppose,  for  instance. 


»  I  may  here  remark  that  Del-  dinm,   Epidendnim,  Phaius,  and 

pino  (' Fecondazione  nelle  Piante,*  Dendrobium,  and  is  able  to  con« 

Firenze,  1867,  p.  19)  says  he  has  firm  in  general  my  statements, 
examined  flowers  of  Vanda,  Ouci- 


156  YANDEX.  Chap.  VL 

the  stigma  to  be  seated  at  the  bottom  of  a  deep  cavity, 
low  down  in  the  column,  or  the  anther  to  be  seated 
higher  up,  or  the  pedicel  of  the  rostellum  to  slope 
more  upwards,  &c. — all  of  which  contingencies  occur 
in  various  species, — in  such  cases,  an  insect  with  a 
pollinium  attached  to  its  head,  if  it  flew  to  another 
flower,  would  not  place  the  pollen-masses  on  the 
stigma,  unless  their  position  had  become  greatly 
changed  after  attachment. 

This  change  is  effected  in  many  Vandese  in  the  same 
manner  as  is  so  general  with  the  Ophreae,  namely,  by  a 
movement  of  depression  in  the  pollinium  in  the  course 
of  about  half  a  minute  after  its  removal  from  the 
rostellum.  I  have  seen  this  movement  conspicuously 
displayed,  generally  causing  the  pollinium  to  rotate 
through  about  a  quarter  of  a  circle,  in  several  species 
of  Oncidium,  Odontoglossum,  Brassia,  Yanda,  Aerides, 
Sarcanthus,  Saccolabium,  Acropera,  and  Maxillaria. 
In  Bodriguezia  suaveolens  the  movement  of  depression 
is  remarkable  from  its  extreme  slowness ;  in  Euloiohia 
viridis  from  its  small  extent.  Mr.  Charles  Wright,  in 
a  letter  to  Professor  Asa  Gray,  says  that  he  observed 
in  Cuba  a  pollinium  of  an  Oncidium  attached  to  a 
humble-bee,  and  he  concluded  at  first  that  I  was 
completely  mistaken  about  the  movement  of  depres- 
sion ;  but  after  several  hours  it  moved  into  the  proper 
position  for  fertilising  the  flower.  In  some  of  the 
cases  above  specified  in  which  the  pollinia  apparently 
undergo  no  movement  of  depression,  I  am  not  sure  that 
there  was  not  a  very  slight  one  after  a  time.  In  the 
various  Ophrese  the  anther-cells  are  sometimes  seated 
exteriorly  and  sometimes  interiorly  with  respect  to 
the  stigma ;  and  there  are  corresponding  outward  and 
inward  movements  in  the  pollinia :  but  in  the  Vandeae 
the   anther-cells   always   lie,  as  far  as  I   have   seen, 


Chap.  VL  MOVEMENTS   OF   THE    POLLINIA.  157 

directly  over  the  stigma,  and  the  movement  of  the 
pollinium  is  always  directly  downwards.  In  Calanthe, 
however,  the  two  stigmas  are  placed  exteriorly  to  the 
anther-cells,  and  the  pollinia,  as  we  shall  see,  are  made 
to  strike  them  by  a  peculiar  mechanical  arrangement 
of  the  parts. 

In  the  Ophrea3  the  seat  of  contraction,  which  causes 
the  act  of  depression,  is  in  the  upper  surface  of  the 
viscid  disc,  close  to  the  point  of  attachment  of  the 
caudicles :  in  most  of  the  Yandeae  the  seat  is  likewise 
in  the  upper  surface  of  the  disc,  but  at  the  point 
where  the  pedicel  is  united  to  it,  and  therefore  at  a 
considerable  distance  from  the  point  of  attachment  of 
the  true  caudicles.  The  contraction  is  hygrometric,  but 
to  this  subject  I  shall  return  in  the  ninth  chapter ; 
therefore  the  movement  does  not  take  place  until  the 
pollinium  has  been  removed  from  the  rostellum,  and 
the  point  of  union  between  the  disc  and  pedicel  has 
been  exposed  for  a  few  seconds  or  minutes  to  the  air. 
If,  after  the  contraction  and  consequent  movement  of 
the  pedicel,  the  whole  body  be  placed  into  water,  the 
pedicel  slowly  moves  back  and  resumes  its  former 
position  with  respect  to  the  viscid  disc.  When  taken 
out  of  water,  it  again  undergoes  the  movement  of  de- 
pression. It  is  of  importance  to  notice  these  facts,  as 
we  thus  get  a  test  by  which  this  movement  can  be 
distinguished  from  certain  other  movements. 

In  Max'illaria  ornithorhyncha,  we  have  a  unique  case. 
The  pedicel  of  the  rostellum  is  much  elongated,  and 
is  entirely  covered  by  the  produced  front  lip  of  the 
anther,  and  is  thus  kept  damp.  When  removed  it 
bends  quickly  backwards  on  itself,  at  about  its  central 
point,  and  thus  becomes  only  half  as  long  as  it  was 
before.  When  placed  in  water  it  resumes  its  original 
straight  form.     If  the  pedicel  had  not  been  in  some 


158  VANDE.E.  Chap.  VI. 

manner  shortened,  it  is  hardly  possible  that  the  flower 
could  have  been  fertilised.  After  this  movement,  the 
pollinium  attached  to  any  small  object  can  be  inserted 
into  the  flower,  and  the  balls  of  pollen  readily  adhere 
to  the  stigmatic  surface.  Here  we  have  an  instance 
of  one  of  those  compensating  actions  in  the  poUinia, 
before  alluded  to,  in  relation  to  the  shallowness  of 
the  stigma. 

In  some  cases,  besides  hygrometric  movements, 
elasticity  comes  into  play.  In  Aerides  odorata  and 
virens,  and  in  an  Oncidium  {roseum  ?),  the  pedicel  of 
the  rostellum  is  fastened  down  in  a  straight  line,  at 
one  extremity  by  the  disc,  and  at  the  other  by  the 
anther ;  it  has,  however,  a  strong  elastic  tendency  to 
spring  up  at  right  angles  to  the  disc.  Consequently, 
if  the  pollinium,  attached  by  its  viscid  disc  to  some 
object,  is  removed  from  the  anther,  the  pedicel  instantly 
springs  up  and  stands  at  nearly  right  angles  to  its 
former  position,  with  the  pollen-masses  carried  aloft. 
This  has  been  noticed  by  other  observers ;  and  I  agree 
with  them  that  the  object  gained  is  to  free  the  pollen- 
masses  from  the  anther-cells.  After  this  upward  elastic 
spring,  the  downward  hygrometric  movement  imme- 
diately commences,  which,  oddly  enough,  carries  the 
pedicel  back  again  into  almost  exactly  the  same 
position,  relatively  to  the  disc,  which  it  held  whilst 
forming  part  of  the  rostellum.  In  Aerides  the  end  of 
the  pedicel,  to  which  the  pollen-masses  are  attached 
by  short  dangling  caudicles,  after  springing  up,  remains 
a  little  curved  upwards;  and  this  curvature  seems 
well  adapted  to  drop  the  pollen-masses  into  the  deep 
stigmatic  cavity  over  the  ledge  in  front.  The  differ- 
ence between  the  first  elastic  and  the  second  or  re- 
versed hygrometric  movement,  was  well  shown  by 
placing  the  pollinium  of   the   above  Oncidium   into 


Chap.  VI.  MOVEMENTS   OF   THE   rOLLlNIA.  159 

water,  after  both  movements  had  taken  phice ;  and 
the  pedicel  then  moved  into  the  same  position  which 
it  had  at  first  assumed  through  its  elasticity  ;  this 
movement  not  being  in  any  way  affected  by  the 
water.  When  taken  out  of  water  the  hygrometric 
movement  of  depression  soon  commenced  for  tlie 
second  time. 

In  Bodrigiiezia  secunda  there  was  no  hygrometric 
movement  of  depression  in  the  pedicel  as  in  the  before- 
mentioned  R.  suaveolenSy  but  there  was  a  rapid  down- 
ward movement,  due  to  elasticity,  and  of  this  I  have 
seen  no  other  instance ;  for  when  the  pedicel  was  put 
into  water  it  showed  no  tendency  to  recover  its  original 
position,  as  occurred  in  many  other  cases. 

In  Phal^nopsis  grandifiora  and  amahilis  the  stigma 
is  shallow  and  the  pedicel  of  the  rostellum  long. 
Some  compensating  action  is  therefore  requisite,  which, 
differently  from  that  in  Maxillaria  ornitJwrhyncJia  is 
effected  by  elasticity.  There  is  no  movement  of  de- 
pression ;  but,  when  the  pollinium  is  removed,  the 
straight  pedicel  suddenly  curls  up  in  the  middle,  thus 
(  — '^— ■  ) :  the  full-stop  on  the  left  hand  may  re- 
present the  balls  of  pollen,  and  the  thick  hyphen  to 
the  right  may  be  supposed  to  represent  the  triangu- 
larly shaped  disc.  The  pedicel  does  not  straighten 
itself  when  placed  in  water.  The  end  carrying  the 
balls  of  pollen  is  a  little  raised  up  after  this  elastic 
movement,  and  the  pedicel,  with  one  end  raised,  and 
with  the  middle  part  upwardly  bowed,  is  well  adapted 
to  drop  the  pollen-masses  into  the  deep  stigmatic 
cavity,  over  a  ledge  in  front.  Fritz  Midler  informs 
me  of  a  case  in  which  the  shortening  of  a  very  long 
pedicel  is  effected  partly  by  elasticity  and  partly  by  a 
hygrometric  movement.  A  small  Ornithocephalus, 
growing   in    South  Brazil,  has  a  very  long   pedicel, 


160 


VANDE^. 


Chap.  IV. 


which  is  shown  closely  attached  to  the  rostellum  in 
the  accompanying  figure  A. 

Fig.  25. 


POLLINIUM  OF  Ornithocepiialus.     (From  a  sketch  by  Fritz  Miiller.) 


A.  Pollinium  still  attached  to  the 

rostellum  with  the  pollen- 
mass  still  lying  in  the  cli- 
nandrum  on  the  summit  of 
the  column. 

B.  Pollinium  in  the  position  which 


it  first  assumes  from  the  elas- 
ticity of  the  pedicel. 
Pollinium    in    the   position    ul- 
timately   assumed    from    the 
hygrometric  movement. 


The  pedicel  when  freed  suddenly  bends  into  the 
form  represented  at  B,  and  soon  afterwards  owing  to 
the  hygrometric  contraction  curls  up  into  the  odd 
figure  shown  at  C.  When  placed  in  water  it  resumes 
the  form  represented  at  B. 


Chap.  VI. 


CALANTHE   MASUCA. 


161 


In  Gdlanthe  masuca  and  the  hybrid  G.  dominii  the 
structure  is  very  different  to  what  it  is  in  most  other 
VandesB.  We  here  have  two  oval,  pit-like  stigmas 
on  each  side  of  the  rostellum  (fig.  26).  The  viscid 
disc  is  oval  (fig.  B),  and  has  no  pedicel,  but  eight 
masses  of  pollen  are  attached  to  it  by  very  short  and 

Fig.  26. 


c  V.''^ 


Calanthe  masuca. 


pollen-masses. 

the  two  stigmas. 

mouth  of  nectary. 

labellum. 

viscid  disc. 

in  fig.  C,  clinandrura  the  pol- 
len-masses being  removed. 
Flower  viewed  from  above,  with 
the  anther -case  removed, 
showing  the  eight  pollen- 
masses  in  their  proper  position 
within  the  clinandrura.  All 
the  sepals  and  petals  have  been 
cut  away  except  the  labellum. 


B.  Pollen-masses  attached    to    the 

viscid  disc,  seen  from  the 
under  side. 

C.  Flower  in  same  position  as  in  A, 

but  with  the  disc  and  pollen- 
masses  removed,  and  now 
showing  the  deeply  notched 
rostellumand  the  empty  clin- 
andrura in  which  the  pollen 
raasses  lay.  Within  the  left- 
hand  stigma  two  pollen- 
masses  may  be  seen  adhering 
to  its  viscid  surface. 


easily  ruptured  caudicles.  These  pollen-masses  radiate 
from  the  disc  like  the  leaves  of  a  fan.  The  rostellum 
is  broad,  and  its  sides  slope  on  each  side  towards  the 
lateral  pit-like  stigmas.  When  the  disc  is  removed 
the  rostellum  is  seen  (fig.  C)  to  be  deeply  notched 
in  the  middle.  The  labellum  is  united  to  the  column 
almost  up  to  its  summit,  leaving  a  passage  (w,  A)  to 


162  VANDE^.  Chap.  VL 

the  long  nectary  close  beneath  the  rostellum.  The 
labellum  is  studded  with  singular,  wartlike,  globular 
excrescences. 

If  a  thick  needle  be  inserted  into  the  mouth  of  the 
nectary  (fig.  A),  and  then  withdrawn,  the  viscid  disc 
is  removed,  bearing  with  it  the  elegant  fan  of  radiating 
pollen-masses.  These  undergo  no  change  in  position. 
But  if  the  needle  be  now  inserted  into  the  nectary  of 
another  flower,  the  ends  of  the  pollen-masses  neces- 
sarily hit  the  upper  and  laterally  sloping  sides  of  the 
rostellum,  and,  glancing  off  both  ways,  strike  down 
into  the  two  lateral  pit-like  stigmas.  The  thin  cau- 
dicles  being  easily  ruptured,  the  pollen-masses  are  left 
adhering  like  little  darts  to  the  viscid  surface  of  both 
stigmas  (see  left-hand  stigma  in  fig.  C),  and  the  fertili- 
sation of  the  flower  is  completed  in  a  simple  manner 
pleasing  to  behold. 

I  should  have  stated  that  a  narrow  transverse  rim  of 
stigmatic  tissue,  beneath  the  rostellum,  connects  the 
two  lateral  stigmas ;  and  it  is  probable  that  some  of 
the  middle  pollen-masses  may  be  inserted  through  the 
notch  in  the  rostellum,  so  as  to  adhere  to  this  rim. 
I  am  the  more  inclined  to  this  opinion  from  having 
found  in  the  elegant  Calantlie  vestita  the  rostellum 
extending  so  widely  over  the  two  lateral  stigmas,  that 
apparently  all  the  pollen-masses  must  be  inserted 
beneath  its  surface. 

The  Angrdecum  sesqiiipedaJey  of  which  the  large  six- 
rayed  flowers,  like  stars  formed  of  snow-white  wax, 
have  excited  the  admiration  of  travellers  in  Madagascar, 
must  not  be  passed  over.  A  green,  whip-like  nectary 
of  astonishing  length  hangs  down  beneath  the  label- 
lum. In  several  flowers  sent  me  by  Mr.  Bateman  I 
found  the  nectaries  eleven  and  a  half  inches  long,  with 
only  the   lower  inch   and   a  half  filled  with  nectar. 


Chap.  VI.  ANGlliECUM   SESQUIPEDALE.  163 

What  can  be  the  use,  it  may  be  asked,  of  a  nectary  of 
such  disproportionate  length  ?  We  shall,  I  think,  see 
that  the  fertilisation  of  the  plant  depends  on  this 
length,  and  on  nectar  being  contained  only  within  the 
lower  and  attenuated  extremity.  It  is,  however,  sur- 
prising that  any  insect  should  be  able  to  reach  the 
nectar.  Our  English  sphinxes  have  proboscides  as  long 
as  their  bodies  ;  but  in  Madagascar  there  must  be 
moths  with  proboscides  capable  of  extension  to  a  length 
of  between  ten  and  eleven  inches!  This  belief  of 
mine  has  been  ridiculed  by  some  entomologists,  but  we 
now  know  from  Pritz  Miiller  *  that  there  is  a  sphinx - 
moth  in  South  Brazil  which  has  a  proboscis  of  nearly 
sufficient  length,  for  when  dried  it  was  between  ten 
and  eleven  inches  long.  When  not  protruded  it  is 
coiled  up  into  a  spiral  of  at  least  twenty  windings. 

The  rostellum  is  broad  and  foliaceous,  and  arches 
rectangularly  over  the  stigma  and  over  the  orifice  of 
the  nectary  :  it  is  deeply  notched  by  a  cleft  enlarged 
or  widened  at  the  inner  end.  Hence  the  rostellum 
nearly  resembles  that  of  Calanthe  after  the  disc  has 
been  removed  (see  fig.  26,  C).  The  under  surfaces  of 
both  margins  of  the  cleft,  near  their  ends,  are  bordered 
by  narrow  strips  of  viscid  membrane,  easily  removed  ; 
so  that  there  are  two  distinct  viscid  discs.  A  short 
membranous  pedicel  is  attached  to  the  middle  of  the 
upper  surface  of  each  disc ;  and  the  pedicel  carries  a 
pollen-mass  at  its  other  end.  Beneath  the  rostellum 
a  narrow,  ledge-like,  adhesive  stigma  is  seated. 

I  could  not  for  some  time  understand  how  the 
pollinia  of  this  Orchid  were  removed,  or  how  the 
stigma  was  fertilised.     I  passed  bristles  and   needles 


*  See  letter  v\ith  a  drawing  by  Hermann  Miiller,  'Nature,*  187J^, 
p.  223. 


164  YANDEX.  CiiAP.  VI. 

down  the  open  entrance  into  the  nectary  and  through 
the  cleft  in  the  rostellum  with  no  result.  It  then 
occurred  to  me  that,  from  the  length  of  the  nectary, 
the  flower  must  be  visited  by  large  moths,  with  a 
proboscis  thick  at  the  base ;  and  that  to  drain  the  last 
drop  of  nectar,  even  the  largest  moth  would  have  to 
force  its  proboscis  as  far  down  as  possible.  Whether 
or  not  the  moth  first  inserted  its  proboscis  by  the  open 
entrance  into  the  nectary,  as  is  most  probable  from  the 
shape  of  the  flower,  or  through  the  cleft  in  the  ros- 
tellum, it  would  ultimately  be  forced  in  order  to  drain 
the  nectary  to  push  its  proboscis  through  the  cleft, 
for  this  is  the  straightest  course  ;  and  by  slight  pressure 
the  whole  foliaceous  rostellum  is  depressed.  The  dis- 
tance from  the  outside  of  the  flower  to  the  extremity  of 
the  nectary  can  be  thus  shortened  by  about  a  quarter 
of  an  inch.  I  therefore  took  a  cylindrical  rod  one- 
tenth  of  an  inch  in  diameter,  and  pushed  it  down 
through  the  cleft  in  the  rostellum.  The  margins 
readily  separated,  and  were  pushed  downwards  together 
with  the  whole  rostellum.  When  I  slowly  withdrew  the 
cylinder  the  rostellum  rose  from  its  elasticity ,  and 
the  margins  of  the  cleft  were  upturned  so  as  to  clasp 
the  cylinder.  Thus  the  viseid  strips  of  membrane  on 
each  under  side  of  the  cleft  rostellum  came  into  contact 
with  the  cylinder,  and  firmly  adhered  to  it ;  and  the 
pollen-masses  were  withdrawn.  By  this  means  I  suc- 
ceeded every  time  in  withdrawing  the  pollinia ;  and 
it  cannot,  I  think,  be  doubted  that  a  large  moth  would 
thus  act ;  that  is,  it  would  drive  its  proboscis  up  to 
the  very  base  through  the  cleft  of  the  rostellum,  so  as 
to  reach  the  extremity  of  the  nectary ;  and  then  the 
pollinia  attached  to  the  base  of  its  proboscis  would  be 
safely  withdrawn. 

I  did  not  succeed  in  leaving  the  pollen-masses  on 


Chap.  VI.  ANGK^CUM   SESQUIPEDALE.  165 

the  stigma  so  well  as  I  did  in  withdrawing  them.  As 
the  margins  of  the  cleft  rostellum  must  be  upturned 
before  the  discs  adhere  to  a  cylindrical  body,  during 
its  withdrawal,  the  pollen-masses  become  affixed  some 
little  way  from  its  base.  The  two  discs  did  not  always 
adhere  at  exactly  opposite  points.  Now,  when  a  moth 
with  the  pollinia  adhering  to  the  base  of  its  proboscis, 
inserts  it  for  a  second  time  into  the  nectary,  and  exerts 
all  its  force  so  as  to  push  down  the  rostellum  as  far  as 
possible,  the  pollen-masses  will  generally  rest  on  and 
adhere  to  the  narrow,  ledge-like  stigma  which  projects 
beneath  the  rostellum.  By  acting  in  this  manner  with 
the  pollinia  attached  to  a  cylindrical  object,  the  pollen- 
masses  were  twice  torn  off  and  left  glued  to  the  stig- 
matic  surface. 

If  the  Angrsecum  in  its  native  forests  secretes  more 
nectar  than  did  the  vigorous  plants  sent  me  by  Mr. 
Bateman,  so  that  the  nectary  ever  becomes  filled,  small 
moths  might  obtain  their  share,  but  they  would  not 
benefit  the  plant.  The  pollinia  would  not  be  with- 
drawn until  some  huge  moth,  with  a  wonderfully  long 
proboscis,  tried  to  drain  the  last  drop.*  If  such  great 
moths  were  to  become  extinct  in  Madagascar,  assur- 
edly the  Angreecum  would  become  extinct.  On  the 
other  hand,  as  the  nectar,  at  least  in  the  lower  part 
of  the  nectary,  is  stored  safe  from  the  depredation  of 
other  insects,  the  extinction  of  the  Angraecum  would 
probably  be  a  serious  loss  to  these  moths.  We  can 
thus  understand  how  the  astonishing  length  of  the 


*  Mr.  Belt  suggests  (*The  Na-  ment  can  thus  be  accounted  for. 

turalist   in  Nicaragua,*   1874,   p.  I  have  no  doubt  of  the  truth  of 

133)  that  the  great  length  of  the  this   principle,  but   it    is   hardly 

nectary   of  this  plant  serves   to  applicable  here,  as  the  moth  has 

prevent  other   moths   ■whi(;h    are  to  be  cianpelled  to  drive  its  pro- 

not  well-adapted  for  the  fertilisa-  boscis  as  deeply  down  as  posaiblo 

lion  of  the  llowers  from  sucking  into  the  dower, 
the  nectar,  and  that  its  dovel"p- 


166  VANDE^.  Chap.  VI. 

nectary  had  been  acqiured  by  successive  modifications. 
As  certain  moths  of  Madagascar  became  larger  through 
natural  selection  in  relation  to  their  general  conditions 
of  life,  either  in  the  larval  or  mature  state,  or  as  the 
Droboscis  alone  was  lenfrthcned  to  obtain  honev  from 
the  Angraecum  and  other  deep  tubular  flowers,  those 
individual  plants  of  the  Angrsecum  which  had  the 
longest  nectaries  (and  the  nectary  varies  much  in 
length  in  some  Orchids),  and  which,  consequently, 
compelled  the  moths  to  insert  their  proboscides  up  to 
the  very  base,  would  be  best  fertilised.  These  plants 
would  yield  most  ssed,  and  the  seedlings  would 
generally  inherit  long  nectaries;  and  so  it  would  be 
in  successive  generations  of  the  plant  and  of  the  moth. 
Thus  it  would  appear  that  there  has  been  a  race  in 
gaining  length  between  the  nectary  of  the  Angraecum 
and  the  proboscis  of  certain  moths ;  but  the  Angrajcnm 
has  trimnphed,  for  it  flourishes  and  abounds  in  the 
forests  of  Madagascar,  and  still  troubles  each  moth 
to  insert  its  proboscis  as  deeply  as  possible  in  order  to 
drain  the  last  drop  of  nectar. 

I  could  add  descriptions  of  many  other  curious 
structures  in  the  Vandeae,  more  especially  from  the 
letters  of  Fritz  Miiller  with  respect  to  those  of  Brazil ; 
but  the  reader  would  be  w^earied.  I  must,  however, 
make  a  few  remarks  on  certain  genera,  the  fertilisation 
of  which  remains  a  mystery,  chiefly  on  account  of  the 
narrowness  of  the  mouth  of  the  stigma,  as  this  renders 
the  insertion  of  the  pollen-masses  extremely  difficult. 
Two  closely  allied  species  or  varieties  of  Acropera,  viz., 
A.  luteola  and  loddigesii  have  been  observed  by  me 
during  several  seasons,  and  every  detail  of  their  struc- 
ture seems  as  if  specially  adapted  to  render  their 
fertilisation  almost  impossible.     I  have  met  with  hardly 


CuAi'.  VI.       ACROPERA,   AND   SOME    ALLIED   GENERA.    167 

any  other  such  case,  not  that  I  fully  understand  the 
contrivances  in  any  Orchid,  for  new  and  admirable 
ones  become  apparent,  the  longer  I  study  even  one  of 
our  commonest  British  species. 

The  thin  and  elongated rostellum  of  Acropera  projects 
at  right  angles  to  the  column  (see  diagram,  fig.  23,  p. 
150) ;  and  the  pedicel  of  the  pollinium  is  of  course 
equally  long  and  much  thinner.  The  disc  consists  of 
an  extremely  small  cap,  viscid  within,  which  fits  on 
the  extremity  of  the  rostellum.  The  viscid  matter 
sets  hard  but  slowly.  The  upper  sepal  forms  a  hood 
enclosing  and  protecting  the  column.  The  labellum 
is  an  extraordinary  organ,  baffling  all  description :  it 
is  articulated  to  the  column  by  a  thin  strap,  so  elastic 
and  flexible  that  a  breath  of  wind  sets  it  vibrating. 
It  hangs  downwards ;  and  the  retention  of  this  posi- 
tion seems  to  be  of  importance,  for  the  footstalk  (ova- 
rium) of  each  flower  is  curved  into  a  semicircle,  so 
as  to  compensate  for  the  pendulous  habit  of  the  plant. 
The  two  upper  petals  and  the  lateral  lobes  of  the 
labellum  serve  as  guides  leading  into  the  hood-like 
upper  sepal. 

The  pollinium,  when  adhering  by  its  disc  to  an 
object,  undergoes  the  common  movement  of  depression  ; 
and  this  seems  superfluous,  for  the  stigmatic  cavity  lies 
(see  diagram,  fig.  23)  high  up  at  the  base  of  the  rect- 
angularly projecting  rostellum.  •  But  this  is  a  com- 
paratively trifling  difficulty  ;  the  real  difficulty  lies  in 
the  orifice  of  the  stigmatic  chamber  being  so  narrow 
that  the  pollen-masses,  though  consisting  of  thin  sheets, 
can  hardly  be  forced  in.  I  repeatedly  tried,  and  suc- 
ceeded only  three  or  four  times.  Even  after  leaving 
them  to  dry  for  four  hours  before  a  fire,  and  thus  to 
shrink  a  little,  I  rarely  succeeded  in  forcing  them 
into  the  stigma.     I  examined  quite  young  flowers  and 


168  VANDEiE.  Chap.  T1 

almost  withered  ones,  for  I  imagined  that  the  mouth 
of  the  chamber  might  be  of  larger  size  at  some  period 
of  growth ;  but  the  difficulty  of  insertion  remained 
the  same.  Now  when  we  observe  that  the  viscid  disc 
is  extraordinarily  small,  and  consequently  its  power  of 
attachment  not  so  firm  as  with  Orchids  having  a  large 
disc,  and  that  the  pedicel  is  very  long  and  thin,  it 
would  seem  almost  indispensable  that  the  stigmatic 
chamber  should  be  unusually  large  for  the  easy 
insertion  of  the  pollinium,  instead  of  being  much  con- 
tracted. Moreover,  the  stigmatic  surface,  as  Dr.  Hooker 
has  likewise  observed,  is  singularly  little  adhesive ! 

The  flowers  when  ready  for  fertilisation  do  not 
secrete  nectar ;  *  but  this  is  no  difficulty,  for  as  Dr. 
Criiger  has  seen  humble-bees  gnawing  the  projections 
on  the  labellum  of  the  closely  allied  Gongora  maculata, 
there  can  be  little  doubt  that  the  distal  cup-shaped 
part  of  the  labellum  of  Acropera  offers  a  similar  at- 
traction to  insects.  After  numberless  trials  in  many 
ways,  I  have  found  that  the  poUinia  can  be  removed 
with  certainty  only  by  pushing  the  rostellum  a  little 
upwards  with  a  camel-hair  brush,  held  in  such  a 
position  that  the  tip  slides  along  the  under  side  of  the 
rostellum,  so  as  to  brush  off  the  little  viscid  cap  on  its 
extremity,  into  which  the  hairs  enter  and  are  glued 
fast.  I  further  find  that  if  the  brush  with  a  pollinium 
thus  attached  to  its  tip  is  pushed  into  and  then  with- 
drawn from  the  stigmatic  cavity,  the  mouth  of  which 
is  furnished  with  a  sharp  ridge,  the  end  of  the  pedicel 


*  Mr.  Scott  las  observed  that  at  no  other  time  couLl  he  find  a 

after  the  flowers  of  A'-ropera  and  trace  of  nectar.     This  exudation 

of  two  species  in  the  allied  genus  can,  therefore,  be  of  no  use  to  the 

of  Gongora  have  been  fertilised,  plant  with  respect  to  its   fertili- 

an   abundance  of  nectar  exudes  sation,  and  must  be  viewed  as  an 

from  the  front  of  the  column ;  but  excretion. 


Chap.  VI.     ACKOPERA,   AND   SOME   ALLIED   GENERA.     169 

which  bears  the  viscid  cap  is  often  left  sticking  within 
the  chamber,  with  the  pollen-masses  close  outside. 
Many  flowers  were  thus  treated,  and  three  of  them 
produced  fine  capsules.  Mr.  Scott  also  succeeded  in 
fertilising  two  flowers  in  the  same  apparently  unnatural 
manner,  as  he  likewise  did  on  one  occasion  by  placing 
a  pollen-mass,  moistened  with  the  viscid  matter  from  a 
distinct  kind  of  Orchis,  at  the  mouth  of  the  stigmatic 
chamber.  These  facts  lead  me  to  suspect  that  an 
insect  with  the  extremity  of  its  abdomen  produced 
into  a  sharp  point  alights  on  the  flower,  and  then  turns 
round  to  gnaw  the  distal  portion  of  the  labellum.  In 
doing  so  it  removes  the  pollinium,  the  viscid  cap  of 
which  adheres  to  the  extremity  of  its  abdomen.  The 
insect  then  visits  another  flower,  by  which  time  the 
movement  of  depression  will  have  caused  the  pedicel 
to  lie  flat  on  its  back ;  and  from  occupying  the  same 
position  as  before,  the  insect  will  be  apt  to  insert  the 
end  of  its  abdomen  into  the  stigmatic  chamber,  and 
the  viscid  cap  will  then  be  scraped  off  by  the  ledge  in 
front,  and  the  pollen-masses  will  be  left  close  outside, 
as  in  the  above  experiments.  The  whole  operation 
would  probably  be  aided  by  the  oscillatory  movement 
of  the  labellum  whilst  gnawed  by  an  insect.  This 
whole  view  is  very  improbable,  but  it  is  the  only  one, 
as  far  as  I  can  see,  which  explains  the  fertilisation  of 
the  flower. 

The  allied  genera  Gongora,  Acineta,  and  Stanhopea 
present  nearly  the  same  difficulty  from  the  narrowness 
of  the  entrance  into  the  stigmatic  chamber.  Mr. 
Scott  tried  repeatedly  but  in  vain  to  force  the  pollen- 
masses  into  the  stigma  of  Gongora  atro-purpurea  and 
truncata  ;  but  he  readily  fertilised  them  by  cutting  off 
the  clinandrum  and  placing  pollen-masses  on  the  now 
exposed   stigma;  as   he  likewise   did   in   the  case  of 


170  VANDE.E.  Chap.  VL 

Acropera.  Dr.  Criiger  Scays*  that  Gongora  macuJata 
"often  bears  fruit  in  Trinidad.  It  is  visited,  exclu- 
sively during  the  day,  as  far  as  I  can  see,  by  a  splendid 
bee,  probably  a  Euglossa,  but  with  the  tongue  nearly 
twice  as  long  as  the  body.  The  tongue  passes  out 
behind  the  abdomen,  and  is  there  curved  upwards. 
As  these  bees  only  come  for  biting  and  gnawing  the 
anterior  side  of  the  labellum,  the  protruding  tongue 
touches  or  approaches  the  gland  (i.  e.,  viscid  disc)  at 
every  retrograde  movement  of  the  insect.  By  this  it 
can  hardly  fail  to  be  loaded  sooner  or  later  with  the 
pollen-masses,  which  are  then  easily  inserted  into  the 
stigmatic  cleft.  I  have,  however,  not  as  yet  observed 
this  fact."  I  am  surprised  that  JDr.  Criiger  should 
speak  of  the  pollen-masses  being  easily  inserted,  and  I 
suppose  that  he  must  have  experimented  with  dried 
and  shrunken  ones.  The  doubled-up,  immensely  elon- 
gated proboscis,  projecting  beyond  the  abdomen,  would 
answer  as  well  as  a  pointed  extremity  to  the  abdomen, 
which  in  the  case  of  Acropera  I  imagine  is  the  instru- 
ment for  removing  the  pollen-masses  ;  but  I  presume 
that  with  Gongora  it  is  not  the  viscid  disc,  but  the 
broad  and  free  ends  of  the  pollen-masses  which  are  in- 
serted into  the  stigmatic  cavity.  As  in  the  case  of 
Acropera,  I  found  it  scarcely  possible  to  insert  the 
pollen-masses  of  Gongora  into  the  stigma ;  but  some 
which  were  removed  from  the  anther  and  left  exposed 
to  the  sun  for  nearly  five  hours,  became  much  shrunk 
and  formed  thin  sheets ;  and  these  could  be  inserted 
without  much  difficulty  into  the  cleft-like  entrance 
of  the  stigma.  The  pollinia  attached  to  an  insect 
flying  about  in  the  torrid  zone  would  shrink  after  a 
time ;    and  the  delay  thus   caused  would  ensure  the 


Jonrn.  I.inn.  Soc,  Bot.'  vol.  viii.  18(j4,  p,  131. 


Chap.  VI.     ACEOPEKA,   AND   SOME   ALLIED   GENERA.     171 

flowers  being  fertilised  with  pollen-  from  a  distinct 
plant. 

With  respect  to  Stanhopea,  Dr.  Criiger  says*  that 
in  the  West  Indies  a  bee  (Euglossa)  often  visits  the 
flowers  for  the  sake  of  gnawing  the  label  lum,  and  he 
caught  one  with  a  pollinium  attached  to  its  back  ;  but 
he  adds  that  he  cannot  understand  how  the  pollen- 
masses  are  inserted  into  the  narrow  mouth  of  the  stigma. 
With  Stanlioi^ea  oculata  I  found  that  the  pollinia  could 
almost  always  be  attached  to  my  naked  or  gloved 
finger,  by  gently  sliding  it  down  the  concave  surface 
of  the  arched  column ;  but  this  occurred  only  within  a 
short  time  after  the  expansion  of  the  flowers,  whilst 
they  are  highly  odoriferous.  By  again  sliding  my 
finger  down  the  column,  the  pollinia  were  almost 
always  rubbed  off  by  the  sharp  edge  of  the  stigmatic 
chamber,  and  were  left  adhering  close  to  its  entrance. 
Flowers  thus  treated  occasionally,  though  rarely, 
yielded  capsules.  The  removal  of  the  pollinia  from 
my  finger  seemed  to  depend  on  the  existence  of  a 
point  projecting  beyond  the  viscid  disc,  and  which  I 
suspect  is  specially  adapted  for  this  purpose.  If  this 
be  so,  the  pollen-masses  must  emit  their  tubes  without 
being  inserted  into  the  stigmatic  chamber.  I  may 
add  that  the  pollen-masses  shrink  very  little  by  being 
thoroughly  dried,  and  could  not  in  this  state  be  easily 
inserted. 

The  entrance  into  the  stigma  is  in  like  manner, 
as  I  hear  from  Fritz  Miiller,  t  so  much  contracted  in 
Cirrhsea  and  Notylia,  which  belong  to  another  sub- 
division of  the  Yandese,  that  the  pollinia  can  be  inserted 


*  Mourn.  Linn.  Soc.  Bot.'  vol.  translation  of  the  first  edition  of 

viii.    1804,    p.    130.      Bronn    has  tliiis  work. 

described  the  structure   of  Stan-  f  'Bot.  Zeitung,'  18G8,  p.  630. 
hopea  devoniemis,  in  his  German 


172  VANDE^.  Chap.  VI. 

into  it  only  with  extreme  difficulty.  In  the  case  of 
Cirrhaea,  he  found  that  this  could  be  effected  more 
easily,  after  they  had  shrunk  a  little  from  being  left 
to  dry  for  half  an  hour  or  an  hour.  He  observed  two 
flowers  with  pollen-masses  naturally  inserted  by  some 
means  into  their  stigmas.  On  several  occasions  aftei 
forcing  the  end  of  a  pollen-mass  into  the  mouth  of  the 
stigma,  he  witnessed  a  most  curious  process  of  deglu- 
tition. The  extremity  of  the  pollen-mass  swells  from 
imbibing  moisture,  and  as  the  chamber  gradually 
widens  downwards,  the  swelling  part  is  forced  down- 
wards ;  so  that  the  whole  is  at  last  drawn  inwards  and 
disappears.  In  the  case  of  Notylia,  Fritz  Miiller  ob- 
served that  the  entrance  into  the  stigma  became  a 
little  larger  after  the  flower  had  remained  expanded 
for  about  a  week.  In  whatever  manner  this  latter 
plant  is  fertilised,  it  is  certain  that  it  must  be  im- 
pregnated with  pollen  from  a  distinct  plant ;  as  it 
offers  one  of  those  extraordinary  cases  in  which  its  own 
pollen  acts  like  poison  on  the  stigma. 

In  the  last  edition  of  this  work  it  was  shown  that 
the  ovaria  of  mature  flowers  of  Acropera  do  not  con- 
tain any  ovules.  But  I  erred  greatly  in  the  interpre- 
tation of  this  fact,  for  I  concluded  that  the  sexes  were 
separate.  I  was  however  soon  convinced  of  my  error 
by  Mr.  Scott,  who  succeeded  in  artificially  fertilising 
the  flowers  with  their  own  pollen.  A  remarkable  dis- 
covery by  Hildebrand,  *  namely,  that  in  many  Orchids 
the  ovules  are  not  developed  unless  the  stigma  is 
penetrated  by  the  pollen-tubes,  and  that  their  develop- 
ment occurs  only  after  an  interval  of  several  weeks 
or  even  months,  explains  the  state  of  the  ovarium 
in  Acropera,  as  observed   by  me.     According  also  to 


♦  'Bot.  Zeitung,'  18G3,  Oct.  30,  et  seq,  and  Aug.  4,  1865. 


CiiAP  VI.  COEYANTIIES.  173 

Fritz  Miiller,  *  the  ovules  of  many  endemic  Epidendrese 
and  Vandeae  in  Brazil  remain  in  a  very  imperfect  state 
of  development  for  some  months,  and  even  in  one  case 
for  half  a  year,  after  the  flowers  had  been  fertilised. 
He  suggests  that  a  plant  which  produces  hundreds  of 
thousands  of  ovules,  would  waste  much  power  if  these 
were  formed  and  did  not  happen  to  be  fertilised,  and 
we  know  that  fertilisation  is  a  doubtful  and  difficult 
operation  with  many  Orchids.  It  would  therefore  be 
an  advantage  to  such  plants,  if  the  ovules  were  not  at 
all  developed  until  their  fertilisation  was  assured  by 
the  pollen- tubes  having  already  penetrated  the  stigma. 

Coryantlies. — I  will  conclude  this  chapter  by  giving 
an  account  of  the  fertilisation  of  the  flowers  of  Cory- 
anthes,  which  is  effected  in  a  manner  that  might  perhaps 
have  been  inferred  from  their  structure,  but  would  have 
appeared  utterly  incredible  had  it  not  been  repeatedly 
witnessed  by  a  careful  observer,  namely,  the  late  Dr. 
Criiger,  Director  of  the  Botanical  Gardens  at  Trinidad. 
The  flowers  are  very  large  and  hang  downwards.  The 
distal  portion  of  the  labellum  (L)  in  the  following  wood- 
cut, fig.  27,  is  converted  into  a  large  bucket  (B).  Two 
appendages  (H),  arising  from  the  narrowed  base  of  the 
labellum,  stand  directly  over  the  bucket  and  secrete  so 
much  fluid  that  drops  may  be  seen  falling  into  it. 
This  fluid  is  limpid  and  so  slightly  sweet  that  it  does 
not  deserve  to  be  called  nectar,  though  evidently  of  the 
same  nature  ;  nor  does  it  serve  to  attract  insects.  M. 
Meniere  estimates  that  the  total  quantity  secreted  by 
a  single  flower  is  about  an  English  ounce,  t  AVhcn 
the  bucket  is  full  the  fluid  overflows  by  the  spout  (P). 


»  'Bot.  Zeitiing,'  1868,  p.  1G4. 

t  *  Bulletin  (ie  la  Soo.  Bot.  dc  Frauoe,'  torn.  ii.  1855,  p.  351. 


171 


VANDE^. 


Chap  VL 


Fig.  27. 


CORYANTilES  SPECIOSA.     (Copied  from  Lindley's  '  Vegetable  Kingdon).') 


L.  labellnm. 

B.  bucket  of  the  labellum. 

H.  fluid-secreting  appendages. 


P.  spout  of  bucket,  orer-archeJ  br 
the  end  of  the  column,  bearing 
the  anther  and  stigma. 


CUAP.  VI.  CORYANTHES.  175 

This  spout  is  closely  over-arched  by  the  end  of  the 
column,  which  bears  the  stigma  and  pollen-masses  in 
such  a  position,  that  an  insect  forcing  its  way  out  of 
the  bucket  through  this  passage  would  first  brush  with 
its  back  against  the  stigma  and  afterwards  against  the 
viscid  discs  of  the  pollinia,  and  thus  remove  them. 
We  are  now  prepared  to  hear  what  Dr.  Criiger  says 
about  the  fertilisation  of  an  allied  species,  the  G. 
macrantha,  the  labellum  of  which  is  provided  with 
crests.*  I  may  premise  that  he  sent  me  specimens  of 
the  bees  which  he  saw  gnawing  these  crests,  and  they 
belong,  as  I  am  informed  by  Mr.  F.  Smith,  to  the  genus 
Euglossa.  Dr.  Criiger  states  that  these  bees  may  be 
"  seen  in  great  numbers  disputing  with  each  other  for 
a  place  on  the  edge  of  the  hypochil  (i.  e.  the  basal  part 
of  the  labellum).  Partly  by  this  contest,  partly  perhaps 
intoxicated  by  the  matter  they  are  indulging  in,  they 
tumble  down  into  the  *  bucket,*  half-full  of  a  fluid 
secreted  by  organs  situated  at  the  base  of  the  column. 
They  then  crawl  along  in  the  water  towards  the 
anterior  side  of  the  bucket,  where  there  is  a  passage 
for  them  between  the  opening  of  this  and  the  column. 
If  one  is  early  on  the  look-out,  as  these  Hymenopterse 
are  early  risers,  one  can  see  in  every  flower  how 
tecundation  is  performed.  The  humble-bee,  in  forcing 
its  way  out  of  its  involuntary  bath,  has  to  exert  itself 
considerably,  as  the  mouth  of  the  epichil  (i.  e.  the 
distal  part  of  the  labellum)  and  the  face  of  the  column 
fit  together  exactly,  and  are  very  stiff  and  elastic.  The 
first  bee,  then,  which  is  immersed  will  have  the  gland 


*  '  Joainal  of  Linn.  Sne.  Bot.*  drawing  of  G.feildlngii  in  '  Jour- 

vol.  viii.  18()4,  p.  130.     There  is  nal  of  Hort.  8oc.'  vol.  iii,  p.  10. 

a  drawinnj  of  this  species  in  Pax-  I  am  indebted  to  Mr.  Thiselton 

toil's  '  Mas;,  of  Botany,'  vol.  v.  p.  Dyer  for  informing  me  of  these 

;H1,  but  it  is  too  complicated  to  be  figurce. 
reproduced.       There    is    also    a 


176  VANDEiE.  Chap.  VI 

of  the  pollen  -mass  glued  to  its  back.  The  insect  then 
generally  gets  through  the  passage,  and  comes  out 
with  this  peculiar  appendage,  to  return  nearly  imme- 
diately to  its  feast,  when  it  is  generally  precipitated  a 
second  time  into  the  bucket,  passing  out  through  the 
same  opening,  and  so  inserting  the  pollen-masses  into 
the  stigma  while  it  forces  its  way  out,  and  thereby  im- 
pregnating either  the  same  or  some  other  flower.  I 
have  often  seen  this ;  and  sometimes  there  are  so  many 
of  these  humble-bees  assembled  that  there  is  a  continual 
procession  of  them  through  the  passage  specified." 

There  cannot  be  the  least  doubt  that  the  fertilisation 
of  the  flower  absolutely  depends  on  insects  crawling 
out  through  the  passage  formed  by  the  extremity  of 
the  labellum  and  the  over-arching  column.  If  the 
large  distal  portion  of  the  labellum  or  bucket  had  been 
dry,  the  bees  could  easily  have  escaped  by  flying  away. 
Therefore  we  must  believe  that  the  fluid  is  secreted  by 
the  appendages  in  such  extraordinary  quantity  and  is 
collected  in  the  bucket,  not  as  a  palatable  attraction 
for  the  bees,  as  these  are  known  to  gnaw  the  labellum, 
but  for  the  sake  of  wetting  their  wings,  and  thus 
compelling  them  to  crawl  out  through  the  passage. 

I  have  now  described,  perhaps  in  too  much  detail, 
a  few  of  the  many  contrivances  by  which  the  VandesR 
are  fertilised.  The  relative  position  and  shape  of  the 
parts — friction,  viscidity,  elastic  and  hygrometric  move- 
ments, all  nicely  related  to  one  another — come  into 
play.  But  all  these  appliances  are  subordinate  to  the 
aid  of  insects.  Without  their  aid,  not  a  plant  belong- 
ing to  this  tribe,  in  the  species  of  the  twenty-nine 
genera  examined  by  me,  would  set  a  seed.  It  is  also 
certain  in  a  majority  of  the  cases,  that  insects  withdraw 
the  pollinia  only  when  retreating  from  the  flower,  and 


UEAP.  VI  CORYANTHES.  177 

by  carrying  them  away,  effect  a  union  between  two 
flowers,  generally  on  distinct  plants.  This  can  hardly 
fail  to  occur  in  all  the  many  cases  in  which  the  pollinia 
slowly  change  their  position,  when  removed  from  the 
rostellum,  in  order  to  assume  a  proper  direction  for 
striking  the  stigma ;  for  the  insects  during  this  in- 
terval will  have  had  time  to  fly  from  the  flowers  on 
cne  plant  which  will  serve  as  the  male,  to  those 
an  another  plant  which  will  serve  as  the  female. 


178  VANDEJE.  Chaf.  YO. 


CHAPTEE  Til. 

VANDEJi:  continued. — catasetid^e 

OatasetidsB,  the  most  remarkable  of  all  Orchids— The  mechanism  by 
which  the  pollinia  of  Catasetum  are  ejected  to  a  distance  and  art, 
transported  by  insects— Sensitiveness  of  the  horns  of  the  rostellura 
—  Extraordinary  diiference  in  the  male,  female,  and  hermaphrodite 
forms  of  Catasetum  tridentatum—Mormodesigiiea,  curious  structure 
of  the  flowers ;  ejection  of  the  pollinia— Mor modes  luxata— Cyc- 
noches  ventricosum,  manner  of  fertilisation. 

1  HAVE  reserved  for  separate  description  one  sub-famil> 
of  the  Vande^,  namely,  the  Catasetidae,  which  must,  I 
think,  be  considered  as  the  most  remarkable  of  all 
Orchids. 

I  will  begin  with  Catasetum.  A  brief  inspection  of 
the  flower  shows  that  here,  as  with  most  other  Orchids, 
some  mechanical  aid  is  requisite  to  remove  the  pollen- 
masses  from  their  cells,  and  to  carry  them  to  the 
stigmatic  surface.  We  shall,  moreover,  presently  see 
that  Catasetum  is  exclusively  a  male  form ;  so  that 
the  pollen-masses  must  be  transported  to  the  female 
plant,  in  order  that  seed  should  be  produced.  The 
pollinium  is  furnished  with  a  viscid  disc  of  huge  size ; 
but  this,  instead  of  being  placed  in  a  position  likely 
to  touch  and  adhere  to  an  insect  visiting  the  flower,  is 
turned  inwards  and  lies  close  to  the  upper  and  back 
surface  of  a  chamber,  which  must  be  called  the  stig- 
matic chamber,  though  functionless  as  a  stigma.  There 
is  nothing  in  this  chamber  to  attract  insects ;  and  even 
if  they  did  enter  it.  the  viscid  surface  of  the  disc  could 
not  possibly  come  into  contact  with  them.      ♦ 


Chap.  Vll.  CATASETUM.  179 

How  then  does  Nature  act  ?  She  has  endowed  these 
plants  with,  what  must  be  called  for  want  of  a  better 
term,  sensitiveness,  and  with  the  remarkable  power  of 
forcibly  ejecting  their  pollinia  even  to  a  considerable 
distance.  Hence,  when  certain  definite  points  of  the 
flower  are  touched  by  an  insect,  the  pollinia  are  shot 
forth  like  an  arrow,  not  barbed  however,  but  having 
a  blunt  and  excessively  adhesive  point.  The  insect, 
disturbed  by  so  sharp  a  blow,  or  after  having  eaten  its 
fill,  flies  sooner  or  later  away  to  a  female  plant,  and, 
whilst  standing  in  the  same  position  as  before,  the 
pollen-bearing  end  of  the  arrow  is  inserted  into  the 
stigmatic  cavity,  and  a  mass  of  pollen  is  left  on  its 
viscid  surface.  Thus,  and  thus  alone,  can  the  five 
species  of  Catasetum  which  I  have  examined  be 
fertilised. 

In  many  Orchideae,  as  in  Listera,  Spiranthes,  and 
Orchis,  the  surface  of  the  rostellum  is  so  far  sensitive, 
that,  when  touched  or  when  exposed  to  the  vapour  of 
chloroform,  it  ruptures  in  certain  defined  lines.  So  it 
is  in  the  tribe  of  the  Catasetidee,  but  with  this  re- 
markable difference,  that  in  Catasetum  the  rostellum  is 
prolonged  into  two  curved  tapering  horns,  or,  as  I  shall 
call  them,  antennae,  which  stand  over  the  labellum 
where  insects  alight.  If  these  are  touched  even  very 
lightly,  they  convey  some  stimulus  to  the  membrane 
which  surrounds  and  connects  the  disc  of  the  pol- 
linium  with  the  adjoining  surface,  causing  it  instantly 
to  rupture;  and  as  soon  as  this  happens  the  disc  is 
suddenly  set  free.  We  have  also  seen  in  several 
Vandeae  that  the  pedicels  of  the  pollinia  are  fastened 
flat  down  in  a  state  of  tension,  and  are  highly  elastic, 
so  that,  when  freed,  they  immediately  spring  up,  appa- 
rently for  the  sake  of  detaching  the  pollen-masses  from 
the   anther-cells.      In  the   genus  Catasetum,  on   the 


180  VANDEJi.  Chap.  VI  t. 

other  liand,  the  pedicels  are  fastened  down  in  a  curved 
position ;  and  when  freed  by  the  rupture  of  the  attached 
edges  of  the  disc,  they  straighten  themselves  with  such 
force,  that  not  only  do  they  drag  the  balls  of  pollen 
together  wdth  the  anther-cells  from  their  places  of 
attachment,  but  the  whole  poUinium  is  jerked  forward, 
over  and  beyond  the  tips  of  the  so-called  antennae,  to 
the  distance  sometimes  of  two  or  three  feet.  Thus, 
as  throughout  nature,  pre-existing  structures  and  capa- 
cities are  utilised  for  new  purposes. 

Catasetum  saccatum.^ — I  will  first  describe  the  male 
forms,  belonging  to  five  species,  which  are  included 
under  the  generic  name  of  Catasetum.  The  general 
appearance  of  the  present  species  is  represented  in  the 
following  woodcut,  fig.  28.  A  side  view  of  the  flower, 
with  all  the  petals  and  sepals  excepting  the  labellum 
cut  off,  is  shown  by  B ;  and  A  gives  a  front  view  of 
the  column.  The  upper  sepal  and  two  upper  petals 
surround  and  protect  the  column ;  the  two  lower  sepals 
project  out  at  right  angles.  The  flower  stands  more 
or  less  inclined  to  either  side,  but  with  the  labellum 
downwards,  as  represented  in  the  drawing.  The  dull 
coppery  and  orange-spotted  tints, — the  yawning  cavity 
in  the  great  fringed  labellum, — the  one  antenna 
projecting  with  the  other  hanging  down — give  to 
these  flow^ers  a  strange,  lurid,  and  almost  reptilian 
appearance. 

In  front  of  the  column,  in  the  middle,  the  deep 
stigmatic  chamber  (fig.  28,  A,  s),  may  be  seen ;  but  this 
is  best  shown  in  the  section  (fig.  29,  C,  s),  in  which  all 


*  I  am  m\\f\).  indel^ted  to  Mr.  mngnificent  collection  of  Orchids, 

James  Veitch  of  Chelsta  for  the  generously  sent  me  two  fine  spikes, 

first    specimen   which    I   saw   of  and  has  aided  me  in  the  kindest 

this   Orchid  ;    f-ub^-equently    Mr.  manner  with  other  specimens. 
S.  Kucker,  so  well  known  for  his 


Chap.  VII.  CATASETUM   SACCATUM.  181 

the  parts  are  a  little  separated  from  each  other,  in 
order  that  the  mechanism  may  be  intelligible.  In 
the  middle  of  the  roof  of  the  stigmatic  chamber,  far 
back  (fZ,  in  A,  fig.  28),  the  upturned  anterior  edge  of 
the  viscid  disc  can  just  be  seen.  The  upper  mem- 
branous surface  of  the  disc,  before  it  is  ruptured,  is 
continuous  with  the  fringed  bases  of  the  two  antennce 
between  which  it  lies.  The  rostellum  projects  over 
the  disc  and  stigmatic  chamber  (see  section  C,  fig.  29), 
and  is  prolonged  on  each  side  so  as  to  form  the  two 
antenna3 ;  the  middle  part  is  covered  by  the  ribbon- 
like pedicel  (jped.)  of  the  pollinium.  The  lower  end  of 
the  pedicel  is  attached  to  the  disc,  and  the  upper  end 
to  the  two  pollen-masses  (jp)  within  the  anther-cell. 
The  pedicel  in  its  natural  position  is  held  much 
bowed  round  the  protuberant  rostellum  ;  when  freed 
it  forcibly  straightens  itself,  and  at  the  same  time  its 
lateral  edges  curl  inwards.  At  an  early  period  of 
growth,  it  is  continuous  with  the  rostellum,  but  sub- 
sequently becomes  separated  from  it  by  the  solution 
of  a  layer  of  cells. 

The  pollinium  when  set  free  and  after  it  has 
straightened  itself,  is  represented  at  D,  fig.  29.  Its 
under  surface,  which  lies  in  contact  with  the  rostellum, 
is  shown  at  E,  with  the  lateral  edges  of  the  pedicel 
now  curled  inwards.  In  this  latter  view,  the  clefts  in 
the  under  sides  of  the  two  pollen-masses  are  shown. 
Within  these  clefts,  near  their  bases,  a  layer  of  strong 
extensible  tissue  is  attached,  forming  the  caudicles,  by 
which  the  pollen-masses  are  united  to  the  pedicel. 
The  lower  end  of  the  pedicel  is  joined  to  the  disc  by  a 
flexible  hinge,  which  occurs  in  no  other  genus,  so  that 
the  pedicel  can  play  backwards  and  forwards,  as  far  as 
the  upturned  end  (fig.  D)  of  the  disc  permits.  The 
disc  is  large  and  thick  ;  it  consists  of  a  strong  upper 


182 


VANDE.E. 


Chap.  VH. 


Fis.  28. 


Catasetum  saccatum 


CuAP.  Vn.  CATASETUM   SACCATUM. 


183 


Fig.  29. 


LATASETUM    SACCATUM. 


a.  anther. 

an  antennae  of  the  rostellum. 

d.  disc  of  polliniuin. 

/.  filament  of  anther. 

g.  germen  or  ovarium. 

I.  labelium. 

p.  pollen-masses. 

pd  or  ped.  pedicel  of  pollinium. 

j>.  stigmatic  chamber. 

A.  Front  view  of  column. 


B.  Side  view  of  flower,  with  all  tlie 

sepals  and  petals  removed  ex- 
cept the  labelium. 

C.  Diagrammatic   section    through 

the  column,  with  all  the  parts 
a  little  separated. 

D.  Pollinium,  upper  surface. 

E.  Pollinium,  lower  surface,  which 

before    removal    lies   in    close 
contact  with  the  rostellum. 


184  VANDE^.  Chap.  VII. 

membrane;  to  which  the  pedicel  is  united,  with  an 
inferior  cushion  of  great  thickness,  of  pulpy,  flocculent, 
and  viscid  matter.  The  posterior  margin  is  much  the 
most  viscid  part,  and  this  necessarily  first  strikes  any 
object  when  the  pollinium  is  ejected.  The  viscid 
matter  soon  sets  hard.  The  whole  surface  of  the  disc 
is  kept  damp  before  ejection,  by  resting  close  against 
the  roof  of  the  stigmatic  chamber ;  but  in  the  section 
(fig.  C)  it  is  represented,  like  the  other  parts,  a  little 
separated  from  the  roof. 

The  connective  membrane  of  the  anther  {a  in  all  the 
figures)  is  produced  into  a  spike,  which  adheres  loosely 
to  the  pointed  end  of  the  column ;  this  pointed  end 
(/,  fig.  C)  is  homologically  the  filament  of  the  anther. 

The  anther  has  this  peculiar  shape  apparently  for 
the  sake  of  leverage,  so  that  it  may  be  easily  torn  off 
by  a  pull  at  its  lower  end,  when  the  pollinium  is 
jerked  out  by  the  elasticity  of  the  pedicel. 

The  labellum  stands  at  right  angles  to  the  column, 
or  hangs  a  little  downwards ;  its  lateral  and  basal 
lobes  are  turned  under  the  middle  portion,  so  that  an 
insect  can  stand  only  in  front  of  the  column.  In  the 
middle  of  the  labellum  there  is  a  deep  cavity,  bordered 
by  crests.  This  cavity  does  not  secrete  nectar,  but  its 
walls  are  thick  and  fleshy,  with  a  slightly  sweet  nutri- 
tious taste ;  and  it  will  presently  be  shown  that  they 
are  gnawed  by  insects.  The  extremity  of  the  left- 
hand  antenna  stands  immediately  over  the  cavity,  and 
would  infalliby  be  touched  by  an  insect  visiting  this 
part  of  the  labellum  for  any  purpose. 

The  antennae  are  the  most  singular  organs  of  the 
flower,  and  occur  in  no  other  genus.  They  form  rigid, 
curved  horns,  tapering  to  a  point.  They  consist  of  a 
narrow  ribbon  of  membrane,  with  the  edges  curled  in* 
wards  so  as  to  touch ;  each  horn  therefore  is  tubular, 


Chap.  VII.  CATASETUM    SACCATUM.  185 

with  a  slit  down  one  side,  like  an  adder's  fang.  They 
are  composed  of  numerous,  much  elongated,  generally 
hexagonal  cells,  pointed  at  both  ends ;  and  these  cells 
(like  those  in  most  of  the  other  tissues  of  the  flower) 
have  nuclei  with  nucleoli.  The  antennae  are  prolonga- 
tions of  the  sides  of  the  anterior  face  of  the  rostellum. 
As  the  viscid  disc  is  continuous  with  a  little  fringe  of 
membrane  on  each  side,  and  as  this  fringe  is  continuous 
with  the  bases  of  the  antennae,  these  latter  organs  are 
put  into  direct  connection  with  the  disc.  The  pedicel 
of  the  pollinium  passes,  as  already  stated,  between  the 
bases  of  the  two  antennae.  The  antennae  are  not  free 
for  their  whole  length ;  but  their  exterior  edges  are 
firmly  united  to  and  blend  for  a  considerable  space 
with  the  margins  of  the  stigmatic  chamber. 

In  all  the  flowers  which  I  examined,  taken  from 
three  plants,  the  two  antennae  which  are  alike  in 
structure  occupied  the  same  relative  position.  The 
extreme  part  of  the  left-hand  antenna  bends  upwards 
(see  B,  fig.  28,  in  which  the  position  is  shown  plainer 
than  in  A),  and  at  the  same  time  a  little  inwards,  so 
that  its  tip  is  medial  and  guards  the  entrance  into 
the  cavity  of  the  labellum.  The  right-hand  antenna 
hangs  down,  with  its  tip  turned  a  little  outwards ;  and 
as  we  shall  immediately  see,  is  almost  paralysed,  so  as 
to  be  functionless. 

Now  for  the  action  of  the  parts.  When  the  left- 
hand  antenna  of  this  species  (or  either  of  the  antennae 
in  three  of  the  following  species)  is  touched,  the  edges 
of  the  upper  membrane  of  the  disc,  which  are  con- 
tinuously united  with  the  surrounding  surface,  instantly 
rupture,  and  the  disc  is  set  free.  The  highly  elastic 
pedicel  then  instantly  flirts  the  heavy  disc  out  of  the 
stigmatic  chamber  with  such  force,  that  the  whole 
pollinium  is  ejected,  bringing  away  with  it  the  two 


186  VANDEJ5.  Chap.  VU. 

balls  of  pollen,  and  tearing  tlie  loosely  attached  spike- 
like anther  from  the  top  of  the  column.  The  pollinium 
is  always  ejected  with  its  viscid  disc  foremost.  I 
imitated  the  action  with  a  minnte  strip  of  Avhalebone, 
slightly  weighted  at  one  end  to  represent  the  disc; 
this  was  then  bent  half  round  a  cylindrical  object, 
the  upper  end  being  at  the  same  time  gently  held  by 
the  smooth  head  of  a  pin,  to  represent  the  retarding 
action  of  the  anther,  the  lower  end  was  then  suddenly 
set  free,  and  the  whalebone  was  pitched  forward,  like 
the  pollinium  of  the  Catasetum,  with  the  weighted 
end  foremost. 

That  the  disc  is  first  jerked  out  of  the  stigmatic 
chamber,  I  ascertained  by  pressing  the  middle  of  the 
pedicel ;  and  when  I  touched  the  antenna  the  disc 
instantly  sprung  forth,  but,  owing  to  the  pressure  on 
the  pedicel,  the  pollinium  was  not  dragged  out  of  the 
anther-cell.  Besides  the  spring  from  the  straighten- 
ing of  the  pedicel,  elasticity  in  a  transverse  direction 
comes  into  play  :  if  a  quill  be  split  lengthways,  and 
the  half  be  forced  longitudinally  on  a  too  thick  pencil, 
immediately  the  pressure  is  removed  the  quill  jumps 
off;  and  an  analogous  action  takes  place  with  the 
pedicel  of  the  pollinium,  owing  to  the  sudden  inward 
curling  of  its  edges,  when  set  free.  These  combined 
forces  suffice  to  eject  the  pollinium  with  considerable 
force  to  the  distance  of  two  or  three  feet.  Several 
persons  have  told  me  that,  when  touching  the  flowers 
of  this  genus  in  their  hothouses,  the  pollinia  have 
.struck  their  faces.  I  touched  the  antennsB  of  C.  cal- 
losum  whilst  holding  the  flower  at  about  a  yard's 
distance  from  a  window,  and  the  pollinium  hit  the 
pane  of  glass,  and  stuck  by  its  adhesive  disc,  to  the 
smooth  vertical  surface. 

The   following  observations  on  the  nature   of  the 


Chap.  VII.  CATASETUM.  187 

excitement  wliich  causes  the  disc  to  separate  from  the 
surrounding  parts,  include  some  made  on  the  following 
species.  Several  flowers  were  sent  me  by  post  and  by 
the  railroad,  and  must  have  been  much  jarred,  but 
they  had  not  exploded.  I  let  two  flowers  fall  from  a 
height  of  two  or  three  inches  on  the  table,  but  the 
poUinia  were  not  ejected.  I  cut  off  with  a  crash  with 
a  pair  of  scissors  the  thick  labellum  and  ovarium 
close  beneath  the  flower ;  but  this  violence  produced 
no  effect.  Nor  did  deep  pricks  in  various  parts  of  the 
column,  even  within  the  stigmatic  chamber.  A  blow, 
sufficiently  hard  to  knock  off  the  anther,  causes  the 
ejection  of  the  pollinium,  as  occurred  to  me  once 
by  accident.  Twice  I  pressed  rather  hard  on  the 
pedicel,  and  consequently  on  the  underlying  ■  ros- 
tellum,  without  any  effect.  Whilst  pressing  on  the 
pedicel,  I  gently  removed  the  anther,  and  then  the 
pollen-bearing  end  of  the  pollinium  sprang  up  from 
its  elasticity,  and  this  movement  caused  the  disc  to 
separate.  M.  Meniere,*  however,  states  that  the 
anther-case  sometimes  detaches  itself,  or  can  be  gently 
detached,  without  the  disc  separating ;  and  that  then 
the  upper  end  of  the  pedicel,  bearing  the  pollen-masses, 
swings  downwards  in  front  of  the  stigmatic  chamber. 

After  trials  made  on  fifteen  flowers  of  three  species, 
I  find  that  no  moderate  degree  of  violence  on  any 
part  of  the  flower,  except  on  the  antennae,  produces 
any  effect.  But  when  the  left-hand  antenna  of  G. 
saccatum,  or  either  antenna  of  the  three  following 
species,  is  touched,  the  pollinium  is  instantly  ejected. 
The  extreme  tip  and  the  whole  length  of  the  antennae 
are  sensitive.  In  one  specimen  of  G.  tridentatum  a 
touch   from  a  bristle  sufficed ;    in   five   specimens   of 


*  '  Bull,  (le  la  Soc.  Bot.  de  France,'  torn.  i.  1854,  p.  367. 


188  VANDE^.  Chap.  VII 

(7.  saccafum  a  gentle  touch  from  a  fine  needle  was 
necessary  ;  but  in  four  other  specimens  a  slight  blow 
was  requisite.  In  G.  tridentatum  a  stream  of  air  and 
of  cold  water  from  a  small  pipe  did  not  suffice ;  nor 
in  any  case  did  a  touch  from  a  human  hair ;  so  that 
the  antennae  are  less  sensitive  than  the  rostellum  of 
Listera.  Such  extreme  sensitiveness  would  indeed 
have  been  useless  to  the  plant,  for,  as  is  now  known, 
the  flowers  are  visited  by  powerful  insects. 

That  the  disc  does  not  separate  owing  to  the  simple 
mechanical  movement  of  the  antennae  is  certain;  for 
they  adhere  firmly  for  a  considerable  space  to  the 
sides  of  the  stigmatic  chamber,  and  are  thus  im- 
movably fixed  near  their  bases.  If  a  vibration  is 
conveyed  along  them,  it  must  be  of  some  special 
nature,  for  ordinary  jars  of  manifold  greater  strength 
do  not  excite  the  act  of  rupture.  The  flowers  in  some 
cases,  when  they  first  arrived,  were  not  sensitive,  but 
after  the  cut-off  spikes  had  stood  for  a  day  or  two  in 
water  they  became  sensitive.  Whether  this  was  owing 
to  fuller  maturity  or  to  the  absorption  of  water,  I  know 
not.  Two  flowers  of  C.  caUosum,  which  were  completely 
torpid,  were  immersed  in  tepid  water  for  an  hour ; 
and  then  the  antennae  became  highly  sensitive ;  this 
indicates  either  that  the  cellular  tissue  of  the  antennae 
must  be  turgid  in  order  to  receive  and  convey  the 
effects  of  a  touch,  or,  as  is  more  probable,  heat  in- 
creases their  sensitiveness.  Two  other  flowers  placed 
in  hot  water,  but  not  so  hot  as  to  scald  my  fingers, 
spontaneously  ejected  their  pollinia.  A  plant  of  C. 
tridentatum  had  been  kept  for  some  days  in  a  rather 
cool  house,  and  tiie  antennae  were  consequently  in  a 
torpid  condition ;  f.  flower  was  cut  off  and  placed  in 
water  at  a  temperature  of  100''  F.  (37-7°  C),  and  no 
effect   w*:s    immsd  lately  produced ;    but  when  it   was 


Chap.  VII.  CATASETUM.  189 

looked  at  after  an  interval  of  1^  30™  tlie  pollinium  was 
found  ejected.  Another  flower  was  placed  in  water  at 
90"  F.  (32-2"  C),  and  after  25™-  the  pollininm  was  found 
ejected :  two  other  flowers  left  for  20™-  in  water  at 
87°  F.  (30*5°  C.)  did  not  explode,  though  they  were  after- 
wards proved  to  be  sensitive  to  a  slight  touch.  Lastly, 
four  flowers  were  placed  in  water  at  83°  F.  (28-3°  C.j  ; 
two  of  these  did  not  eject  their  pollinia  in  45™,  and 
were  then  found  to  be  sensitive  ;  whereas  the  other  two, 
when  looked  at  after  1^  15™-,  had  spontaneously  ejected 
their  pollinia.  These  cases  show  that  immersion  in 
water  raised  to  a  temperature  only  a  little  higher  than 
that  to  which  the  plant  had  been  exposed,  causes  the 
membrane  by  which  the  discs  are  attached  to  rupture. 
A  thin  stream  of  almost  boiling  water  was  allowed  to 
fall  through  a  fine  pipe  on  the  antenna3  of  some  flowers 
on  the  above  plant ;  these  were  softened  and  killed 
but  the  pollinia  were  not  ejected.  Nor  did  sulphuric 
acid,  dropped  on  the  tips  of  the  antennae,  cause  any 
action  ;  though  their  upper  parts  which  had  not 
been  injured  by  the  acid  were  afterwards  found  to  bo 
sensitive  to  a  touch.  In  these  two  latter  cases,  I 
presume  that  the  shock  was  so  sudden  and  violent 
that  the  tissue  was  instantly  killed.  Considering 
the  above  several  facts,  we  may  infer  that  it  must 
be  some  molecular  change  which  is  conveyed  along 
the  antennae,  causing  the  membrane  round  the  discs  to 
rupture.  In  G,  tridentatum  the  antenna?  were  one  inch 
and  a  tenth  in  length,  and  a  gentle  touch  from  a  bristle 
on  the  extreme  tip  was  conveyed,  as  far  as  I  could 
perceive,  instantaneously  throughout  this  length.  I 
measured  several  cells  in  the  tissue  composing  the 
antennae  of  this  species,  and  on  a  rough  average  it 
appeared  that  the  stimulus  must  travel  through  no  less 
than  from  seventy  to  eighty  cells. 


190  VANDE^.  Chap.  VII. 

We  may,  at  least,  safely  conclude  that  the  antennge, 
which  are  characteristic  of  the  genus  Catasetum,  are 
specially  adapted  to  receive  and  convey  the  effects  of 
a  touch  to  the  disc  of  the  pollinium.  This  causes  the 
membrane  to  rupture,  and  the  pollinium  is  then  ejected 
by  the  elasticity  of  its  pedicel.  If  we  required  further 
proof,  nature  affords  it  in  the  case  of  the  so-called 
genus  Monachanthus,  which,  as  we  shall  presently  see^ 
is  the  female  of  Catasetum  tridentatum,  and  it  does  not 
possess  pollinia  which  can  be  ejected,  and  the  antennae 
are  here  entirely  absent. 

I  have  stated  that  in  C.  saccatiim  the  right-hand 
antenna  invariably  hangs  down,  with  the  tip  turned 
slightly  outwards,  and  that  it  is  almost  paralysed.  I 
ground  my  belief  on  five  trials,  in  which  I  violently 
hit,  bent,  and  pricked  this  antenna,  and  this  produced 
no  effect ;  but  when  immediately  afterwards  the  left- 
hand  antenna  was  touched  with  much  less  force,  the 
pollinium  was  shot  forth.  In  a  sixth  case  a  forcible 
blow  on  the  right-hand  antenna  did  cause  the  act  of 
ejection,  so  that  it  is  not  completely  paralysed.  As 
this  antenna  does  not  guard  the  labellum,  which  in  all 
Orchids  is  the  part  attractive,  that  is  to  insects,  its 
sensitiveness  would  be  useless. 

From  the  large  size  of  the  flower,  more  especially 
of  the  viscid  disc,  and  from  its  wonderful  power  of 
adhesion,  I  formerly  inferred  that  the  flowers  were 
visited  by  large  insects,  and  this  is  now  known  to  be 
the  case.  The  viscid  matter  sticks  so  firmly  after  it 
has  set  hard,  and  the  pedicel  is  so  strong  (though  very 
thin  and  only  one-twentieth  of  an  inch  in  breadth  at 
the  hinge),  that  to  my  surprise  a  pollinium  attached 
to  an  object  supported  for  a  few  seconds  a  weight  of 
1262  grains,  or  nearly  three  ounces ;  and  it  supported 
for  a  considerable  time  a  slightly  less  weight.     When 


Chap.  VII. 


CATASETUM. 


191 


the  pollinium  is  shot  forth,  the  large  spike-like  anther 
is  generally  carried  with  it.  If  the  disc  strikes  a  flat 
surface  like  a  table,  the  momentum  from  the  weight 
of  the  anther  often  carries  the  pollen-bearing  end 
beyond  the  disc,  and  the  pollinium  is  thus  affixed  in 
a  wrong  direction  for  the  fertilisation  of  another 
flower,  supposing  it  to  have  been  attached  to  an 
insect's  body.  The  flight  of  the  pollinium  is  often 
rather  crooked.  *  But  it  must  not  be  forgotten  that 
under  nature  the  ejection  is  caused  by  the  antennae 
being  touched  by  a  large  insect  standing  on  the  la- 
bellum,  which  will  thus  have  its  head  and  thorax 
placed  near  to  the  anther.  A  rounded  object  thus 
held  is  always  accurately  struck  in  the  middle,  and 
when  removed  with  the  pollinium  adhering  to  it,  the 
weight  of  the  anther  depresses  the  hinge  of  the  pol- 
linium ;  and  in  this  position  the  anther-case  readily 
drops  off,  leaving  the  balls  of  pollen  free,  in  a  proper 
position  for  fertilising  the  female  flower.     The  utility 


*  M.  Baillon  (•  Bull,  de  la  Soc. 
Bot.  de  France,'  torn.  i.  1854,  p. 
285)  states  that  Gatasetum  luridum 
ejects  its  pollinia  always  in  a 
straight  line,  and  in  such  a  direc- 
tion that  it  sticks  fast  to  the 
bottom  of  the  concavity  of  the 
labellum ;  and  he  imagines  that 
in  this  position  it  fertilises  the 
flower  in  a  manner  not  clearly 
explained.  In  a  subsequent  paper 
in  the  same  volume  (p.  367)  M. 
Me'niere  justly  disputes  M.  Bail- 
Ion's  conclusion.  He  remarks 
that  the  anther-case  is  easily  de- 
tached, and  sometimes  naturally 
detaches  itself ;  the  pollinia  then 
swing  downwards  by  the  elasticity 
of  the  pedicel,  the  viscid  disc  still 
remaining:  attached  to  the  roof 
of  the  stigmatic  chamber.  M. 
Meniere  hints  that,  by  the  subse- 


quent and  progressive  retraction 
of  the  pedicel,  the  pollen-masses 
might  be  carried  into  the  st'gmatic 
chamber.  This  is  not  possible  in 
the  three  species  which  I  have 
examined,  and  would  be  uselej^s. 
But  M.  Meniere  himself  then  goes 
on  to  show  how  important  insects 
are  fur  the  fertilisation  of  Orchids  ; 
and  apparently  infers  that  their 
agency  comes  into  play  with 
Catasetum,  and  that  this  plant 
does  not  fertilise  itself.  Both  INI. 
Baillon  and  M.  Me'niere  correctly 
describe  the  curved  position  in 
wliicli  the  elastic  pedicel  lies 
before  it  is  set  fiee.  Neither  of 
these  botani.-ts  seenis  to  be  aware 
that  the  species  of  Catasetijin 
(at  lea^t  the  five  which  I  have 
examined;  are  exclusively  mole 
plants. 


192  VANDE^.  Chap.  VIL 

of  so  forcible  an  ejection  no  doubt  is  to  drive  the  soft 
and  viscid  cushion  of  the  disc  against  the  hairy  thorax 
of  the  large  hymenopterous  insects  which  frequent  the 
flowers.  When  once  attached  to  an  insect,  assuredly 
no  force  which  the  insect  could  exert  would  remove 
the  disc  and  pedicel ;  but  the  caudicles  are  ruptured 
without  much  difficulty,  and  thus  the  balls  of  pollen 
might  readily  be  left  on  the  adhesive  stigma  of  tlie 
female  flower. 

Gatasetum  callosum. — The  flowers  of  this  species  *  are 
smaller  than  those  of  the  last,  but  resemble  them  in 
most  respects.  The  edge  of  the  labellum  is  covered 
with  papillae ;  the  cavity  in  the  middle  is  small,  and 
behind  it  there  is  an  elongated  anvil-like  projection, 
— facts  which  I  mention  from  the  resemblance  in  some 
of  these  points  between  the  labellum  of  this  species 
and  that  of  Myanthus  harhatus,  the  hermaphrodite  form 
of  Gatasetum  tridentatum,  presently  to  be  described. 
When  either  antenna  is  touched,  the  pollinium  is 
ejected  with  much  force.  The  yellow-coloured  pedicel 
is  much  bowed,  and  is  joined  by  a  hinge  to  the  ex- 
tremely viscid  disc.  The  two  antennae  stand  sym- 
metrically on  each  side  of  the  anvil-like  projection, 
with  their  tips  lying  within  the  small  cavity  of  the 
labellum.  The  walls  of  this  cavity  have  a  pleasant 
nutritious  taste.  The  antennae  are  remarkable,  from 
their  whole  surface  being  roughened  with  papillae. 
The  plant  is  a  male,  and  the  female  form  is  at  present 
unknown. 

Gatasetum  tabular e. — This  species  belongs  to  the 
same  type  as  G.  saceatum,  but  differs  greatly  from  it  in 
appearance.  The  central  portion^  of  the  labellum  con- 
sists of  a  narrow,   elongated,  table-like  projection,  of 

*  A  fine  sp'ke  of  flowers  of  this  Mr.  Kucker,  and  was  named  for 
species   was   kindly  sent  me   by       me  by  Dr.  Lindloy. 


Chap.  YII.  CATASETUM   TEIUENTATUM.  193 

an  almost  white  colour  and  formed  of  a  thick  mass 
of  succulent  tissue,  havino^  a  sweetish  taste.  Towards 
the  base  of  the  labellum  there  is  a  large  cavity,  which 
externally  resembles  the  nectary  of  an  ordinary  flower, 
but  apparently  never  contains  nectar.  The  pointed 
extremity  of  the  left-hand  antenna  lies  within  this 
cavity,  and  would  infallibly  be  touched  by  an  insect 
gnawing  the  bilobed  and  basal  end  of  the  medial  pro- 
jection of  the  labellum.  The  right-hand  antenna  is 
turned  inwards,  with  the  extreme  part  bent  at  right 
angles  and  pressed  against  the  column;  therefore  I 
do  not  doubt  that  it  is  paralysed  as  in  G.  saceatum ; 
but  the  flowers  examined  by  me  had  lost  almost  all 
their  sensitiveness. 

Catasetum  planiceps  {?). — This  species  does  not  differ 
much  from  the  following  one,  so  I  will  describe  it 
briefly.  The  green  and  spotted  labellum  stands  on 
the  upper  side  of  the  flower ;  it  is  jar-shaped,  with 
a  small  orifice.  The  two  elongated  and  roughened 
antennae  lie  coiled  up  some  little  way  apart  and 
parallel  to  one  another,  within  the  labellum.  They 
are  both  sensitive  to  a  touch. 

Catasetum  tridentatum. — The  general  appearance 
of  this  species,  which  is  very  different  from  that  of 
G.  saceatum,  callosum  and  tabular e,  is  represented  in 
fig.  30,  with  a  sepal  on  each  side  cut  off. 

The  flower  stands  with  the  labellum  uppermost,  that 
is,  in  a  reversed  position  compared  with  most  Orchids. 
The  labellum  is  helmet-shaped,  its  distal  portion  being 
reduced  to  three  small  points.  It  cannot  hold  nectar 
from  its  position  ;  but  the  walls  are  thick,  and  have,  as 
in  the  other  species,  a  pleasant  nutritious  taste.  The 
stigmatic  chamber,  though  functionless  as  a  stigma, 
is  of  large  size.  The  summit  of  the  column,  and  the 
spike-like   anther,  are  not   so   much  elongated  as  in 


194 


MONACHANTHUS   VIRIDIS. 


Chap.  Vll. 


C.  saccatwn.  In  other  respects  there  is  no  important 
difference.  The  antennae  are  of  greater  length  ;  their 
tips  for  about  one-twentieth  of  their  length  are 
roughened  by  cells  produced  into  papillae. 

Fig.  30. 


Catasetum  tridentatum. 


a.     anther. 

pd.  pedicel  of  pollinium. 

an.  antennce, 

I.     labellum. 


A.  Side  view  of  flower  in  its  natural 

position,  with  two  of  the  sepals 
cut  off. 

B.  Front  view  of  column,  in  position 

reverse  of  ti^r.  A. 


The  pedicel  of  the  pollinium  is  articulated  as  before 
by  a  hinge  to  the  disc  ;  it  can  move  freely  only  in  one 
direction  owing  to  one  end  of  the  disc  being  upturned, 
and  this  restricted  power  of  movement  apparently 
comes  into  play  when  the  pollinium  is  carried  by  an 
insect  to  the  female  flower.  The  disc  is,  as  in  the  other 
species,  of  large  size,  and  the  end  which  when  ejected 
first  strikes  any  object,  is  much  more  viscid  than  the 
rest  of  the  surface.  This  latter  surface  is  drenched 
with  a  milky  fluid,  which,  when  exposed  to  the  air, 
rapidly  turns  bro^\^l,  and  sets  into  a  cheesy  consistence. 
The  upper  surface  of  the  disc  consists  of  strong  mem* 


Chap.  YJl.  CATASETUM   TllIDENTATUM.  195 

brane  formed  of  polygonal  cells,  resting  on  and  adhering 
to  a  thick  cushion,  formed  of  irregular  rounded  balls 
of  brown  matter,  separated  from  each  other  and  em- 
bedded in  a  transparent,  structureless,  highly  elastic 
substance.  This  cushion  towards  the  posterior  end  of 
the  disc  graduates  into  viscid  matter,  which  when 
consolidated  is  brown,  translucent,  and  homogeneous. 
Altogether  the  disc  of  Catasetum  presents  a  much 
more  complex  structure  than  in  the  other  Yandese. 

I  need  not  further  describe  the  present  species, 
except  as  to  the  position  of  the  antennae.  They  oc- 
cupied exactly  the  same  position  in  all  the  many 
flowers  which  were  examined.  Both  lie  curled  within 
the  helmet-like  labellum ;  the  left-hand  one  stands 
higher  up,  with  its  inwardly  bowed  extremity  in  the 
middle ;  the  right-hand  antenna  lies  lower  down  and 
crosses  the  whole  base  of  the  labellum,  with  the  tip 
just  projecting  beyond  the  left  margin  of  the  base  of 
the  column.  Both  are  sensitive,  but  apparently  the 
one  which  is  coiled  within  the  middle  of  the  labellum 
is  the  more  sensitive  of  the  two.  From  the  position 
of  the  petals  and  sepals,  an  insect  visiting  the  flower 
would  almost  certainly  alight  on  the  crest  of  the  la- 
bellum; and  it  could  hardly  gnaw  any  part  of  the 
great  cavity  without  touching  one  of  the  two  antennae, 
for  the  left-hand  one  guards  the  upper  part,  and  the 
right-hand  one  the  lower  part.  When  either  of  these 
is  touched  the  pollinium  is  ejected  and  the  disc  will 
strike  the  head  or  thorax  of  the  insect. 

The  position  of  the  antennae  in  this  Catasetum  may 
be  compared  with  that  of  a  man  with  his  left  arm  raised 
and  bent  so  that  his  hand  stands  in  front  of  his  chest, 
and  with  his  right  arm  crossing  his  body  lower  down 
so  that  the  fingers  project  just  beyond  his  left  side. 
In  Catasetum  callosim  both  arms  are  hekl  lower  down 


196  VANDE.E.  Chap.  VIL 

and  are  extended  symmetrically.  In  C.  saccatum  the 
left  arm  is  bowed  and  held  in  front,  as  in  C.  triden- 
tat  urn,  but  rather  lower  down ;  whilst  the  right  arm 
hangs  downwards  paralysed,  with  the  hand  turned  a 
little  outwards.  In  every  case  notice  w411  be  given  in 
an  admirable  manner,  when  an  insect  visits  the  label- 
lum,  and  the  time  has  arrived  for  the  ejection  of  the 
pollinium,  so  that  it  may  be  transported  to  the  female 
plant. 

Gatasetmn  tridentatum  is  interesting  under  another 
point  of  view.  Botanists  were  astonished  when  Sir  R. 
Schomburgk*  stated  that  he  had  seen  three  forms, 
believed  to  constitute  three  distinct  genera,  namely, 
Catasetum  tridentatum,  Monachanthus  viridis,  and 
Mijantlius  harbatus,  all  growing  on  the  same  plant. 
Lindley  remarked  t  that  "  such  cases  shake  to  the 
foundation  all  our  ideas  of  the  stability  of  genera  and 
species."  Sir  R.  Schomburgk  affirms  that  he  has  seen 
hundreds  of  plants  of  G.  tridentatum  in  Essequibo  with- 
out ever  finding  one  specimen  with  seeds  ;{  whereas 

*  'Transaciions  of  tlioLinntan  Bristol.      Lastly    Dean    Herbert 

See'  vol.  xvii.  p.   522.     Another  infonned  me  many  years  n go  that 

account  by  Dr.  Lindley  appeared  Cataseium  luridum  flowered  »nd 

in   the  'Lutanicul   Kegister,'  fol.  kept  true   for  nine   years  in  the 

1951,  of  a  distinct  species  of  My-  Botanic  Garden  at  York  ;  it  then 

anthus  and  Monachantlius appear-  threw  up  a  scape  of  a  Myanthus, 

ing  on  the  same  scape  :  he  alludes  which  as  we  shall  pr<  seutly  see  is 

also  to  other  cases.     Some  of  the  an  hermaphrodite,  intermediate  in 

dowers  in  these  cases  were  in  an  in-  form  between  tlie  male  and  f«-male. 

termediate  condition,  which  is  not  ]M.  Duchartro  has  given  a  full  his- 

snrprising,  i^eting  that  in  dioecious  tori'  al  at-couot  of  the  appearance 

plants  we  some tim«siiave  a  pirtial  of  tliese  forms  on  the  same  plant, 

resumption   of  the   characters   of  in    '  Bull,    de    la    Soc.    Bot.    de 

both  sexes.  Mr.  IL  dgers  of  River-  France,'  vol   ix.  1862,  p.  US. 

hill  informs  me  ti. at  he  iinportid  t    The  ^' Vegetable   Kingdom,* 

from  De    erara  a  Myanthus,  and  1S53,  p.  178. 

ti.ai    v\h  n    it  tlowered  a  second  %  Bmngniart  states  ('Bull,  de 

t,i...e  it  was  inetamorphosed  into  la  Soc.  B-t.  de  France,'  toiu.  ii. 

a     Ci.ta^elum.       Dr.      Carpenter  ]8.'i5,  p.  20)  that  M.  Neumann,  a 

('Compan.tive    Physiology,'    4th  gi^ilful  fertiliser  of  Orchids,  could 

e<iit.  p.  tiyS)  alludes  to   an   ana-  never  succeed  in  fertilising  Cata- 

logons   case    which    occurred    at  setum. 


OuAP.  VII.  CATASETUM   TRIDENTATUM.  197 

he  was  surprised  at  the  gigantic  seed-vessels  of  the 
Monachanthus ;  and  he  correctly  remarks  that  "  here 
we  have  traces  of  sexual  difference  in  Orchideous 
flowers."  Dr.  Crusher  also  informs  me  that  in  Trinidad 
he  never  saw  capsules  naturally  produced  by  the 
flowers  of  this  Catasetum  ;  *  nor  when  they  were  fer- 
tilised by  him  with  their  own  pollen,  as  was  done 
repeatedly.  On  the  other  hand,  when  he  fertilised 
the  flowers  of  the  Monaclianihus  viridis  with  pollen 
from  the  Catasetum,  the  operation  never  failed.  The 
Monachanthus  also  commonly  produces  fruit  in  a  state 
of  nature. 

From  what  I  had  myself  observed,  I  was  led  to 
examine  carefully  the  female  organs  of  C.  tridentatum, 
coMosum,  and  saccatum.  In  no  case  was  the  stigmatic 
surface  viscid,  as  it  is  in  all  other  Orchids  (except  as 
we  shall  hereafter  see  in  Cypripedium),  and  as  is 
indispensable  for  securing  the  pollen-masses  by  the 
rupture  of  the  caudicles.  I  carefully  looked  to  this 
point  both  in  young  and  old  flowers  of  G.  tridentatum. 
When  the  surface  of  the  stigmatic  chamber  and  of  the 
stigmatic  canal  of  the  above-named  three  species  is 
scraped  off,  after  having  been  kept  in  spirits,  it  is  found 
to  be  composed  of  utriculi  (including  nuclei  of  the 
proper  shape),  but  not  nearly  so  numerous  as  with 
ordinary  Orchids.     The  utriculi  cohere  more  together 


*  Dr.  Hance  writes  to  me  thnt  often  occurred.     J.  G.  Beer  says 

he  I  as  in  his  collection  a  plant  of  (quoted  by  Irmisch,  •  Beitrage  zu 

Catasetum   tridentatum   from   the  Biolotjie  der  Orchideen,'  1853,  p. 

West  Indies  bearing  a  tine  capsule;  22)  that  during:  three  years  he 

but  it  does  not  appear  to  have  tried  in  vain  to  fertilise  Catasetum, 

lieen   ascertained   that    this   par-  but  on  one  occasion,  by  placing 

ticulur  flower  was  that  of  Cata-  only  the  viscid  disc  of  a  pollinium 

8  turn,  and  there  is  no  great  im-  within    the  stigma,  a  ripe   fruit 

probability  in  a  single  flower  of  was    produced  ;    but    it   may   be 

Monachanthus  being  produced  by  asked,     Did    the   seeds    cuutain 

a  plant  of  Catasetum.  as  well  as  a  embryos? 
whole  scape,  which  we  know  has 


198  VANDE.E.  Chap.  VU. 

and  are  more  transparent ;  T  examined  for  comparison 
those  of  many  kinds  of  Orchids  which  had  been  kept 
in  spirits,  and  in  all  found  them  much  less  transparent. 
In  G,  tridentatunfiy  the  ovarium  is  shorter,  much  less 
deeply  furrowed,  narrower  at  the  base,  and  internally 
more  solid  than  in  Monachanthus.  Again,  in  all 
three  species  of  Catasetum  the  ovule-bearing  cords 
are  short ;  and  the  ovules  present  a  considerably  dif- 
ferent appearance,  in  being  thinner,  more  transparent, 
and  less  pulpy  than  in  the  numerous  other  Orchids 
examined  for  the  sake  of  comparison.  Perhaps  these 
bodies  hardly  ought  to  be  called  ovules,  although  they 
correspond  closely  in  general  appearance  and  position 
with  true  ovules,  for  I  was  unable  in  any  case  to  make 
out  the  opening  of  the  testa  and  the  included  nucleus ; 
nor  were  the  ovules  ever  inverted. 

From  these  several  facts,  namely, — the  shortness, 
smoothness,  and  narrowness  of  the  ovarium,  the  short- 
ness of  the  ovule-bearing  cords,  the  state  of  the  ovules 
themselves,  the  stigmatic  surface  not  being  viscid,  the 
transparent  condition  of  the  utriculi, — and  from  neither 
Sir  R.  Schomburgk  nor  Dr.  Criiger  having  ever  seen 
G.  tridentahmi  producing  seed  in  its  native  home, 
or  when  artificially  fertilised,  we  may  confidently 
look  at  this  species,  as  well  as  the  other  species  of 
Catasetum,  as  male  plants. 

With  respect  to  Monachantlius  viridis,  and  Myanthus 
barhatus,  the  President  of  the  Linnean  Society  has 
kindly  permitted  me  to  examine  the  spike  bearing 
these  two  so-called  genera,  preserved  in  spirits,  which 
was  sent  home  by  Sir  K.  Schomburgk.  The  flower  of 
the  Monachanthus  (A,  fig.  31)  resembles  pretty  closely 
in  external  appearance  that  of  Gatasetum  tridentatum 
(fig.  30).  The  labellum,  which  holds  the  same  relative 
position  to   the   other   parts,  is  not  nearly  so  deep, 


Chap.  VII. 


CATASETUM    TEIDENTATUM. 


190 


especially  on  the  sides,  and  its  edge  is  crenated.  The 
other  petals  and  sepals  are  all  reflexed,  and  are  not  so 
much  spotted  as  in  the  Catasetum.  The  bract  at  the 
base  of  the  ovarium  is  much  larger.   The  whole  column, 

Fig.  81. 


B.  Myanthus  barbatus. 

a.      anther. 

an.    antennae. 

I.       labellum. 

p.      pollen-mass,  rudimentary. 

s.      stigmatic  cleft. 

sep.  two  lower  sepals. 


A.    MONACIIANTIIUS    VIRIDIS. 

A.  Side  view  of  Monachimthus  viri- 

dis  in  its  natural  po.sition.  (The 
shading  in  both  drawings  has 
been  added  from  Mr.  Reiss' 
drawing  in  the  '  Linnean  Trans- 
actions.') 

B.  Side  view  of  Myanthus  harhatui 

in  its  natural  position. 


especially  the  filament  and  the  spike-like  anther,  are 
much  shorter ;  and  the  rostellum  is  much  less  protu- 
berant. The  antennae  are  entirely  absent,  and  the 
pollen-masses  are  rudimentary.     These  are  interesting 


20C  YANDEX.  Chap.  VII. 

facts,  from  corroborating  the  view  taken  of  the  function 
of  the  antennae ;  for  as  there  are  no  pollinia  to  eject, 
an  organ  adapted  to  convey  the  stimulus  from  the 
touch  of  an  insect  to  the  rostellum  would  be  useless. 
I  could  find  no  trace  of  a  viscid  disc  or  pedicel,  and 
no  doubt  they  had  been  lost;  for  Dr.  Criiger  says* 
that  "  the  anther  of  the  female  flower  drops  off  imme- 
diately after  the  opening  of  the  same,  i.  e.  before  the 
flower  has  reached  perfection  as  regards  colour,  size, 
and  smell.  The  disc  does  not  cohere,  or  very  slightly, 
to  the  pollen-masses,  but  drops  off  about  the  same 
time,  with  the  anther ;"  leaving  behind  them  the  rudi- 
mentary pollen-masses. 

Instead  of  a  large  stigmatic  chamber,  there  is  a 
narrow  transverse  cleft  close  beneath  the  small  anther. 
I  was  able  to  insert  one  of  the  pollen-masses  of  the 
male  Catasetum  into  this  cleft,  which  from  having  been 
kept  in  spirits  was  lined  with  coagulated  beads  of 
viscid  matter,  and  with  utriculi.  The  utriculi,  differ- 
ently from  those  in  Catasetum,  were  charged  (after 
having  been  kept  in  spirits)  with  brown  matter.  The 
ovarium  is  longer,  thicker  near  the  base,  and  more 
plainly  furrowed  than  in  Catasetum  ;  the  ovule-bearing 
cords  are  also  much  longer,  and  the  ovules  more  opaque 
and  pulpy,  as  in  all  common  Orchids.  I  believe  that 
I  saw  the  opening  at  the  partially  inverted  end  of  the 
testa,  with  a  large  projecting  nucleus  ;  but  as  the  speci- 
mens had  been  kept  many  years  in  spirits  and  were 
somewhat  altered,  I  dare  not  speak  positively.  From 
these  facts  alone  it  is  almost  certain  that  Monachanthus 
is  a  female  plant;  and  as  already  stated,  Sir  R. 
Schomburgk  and  Dr.  Criiger  have  both  seen  it  seeding 
abundantly.     Altogetlier  the  flower  differs  in  a  most 


*  '  Journ.  Linn.  Soc.  Bot'  vol.  viii.  1864,  p.  127. 


Cbap.  VI].  MONACHAilTHUS   VIRIDIS.  201 

remarkable  manner  from  that  of  the  male  Gatasetum 
tridentatum,  and  it  is  no  wonder  that  the  two  plants 
were  formerly  ranked  as  distinct  genera. 

The  pollen-masses  offer  so  cnrious  and  good  an  illus- 
tration  of  a  structure  in  a  rudimentary  condition,  that 
they  are  worth  description ;  but  I  must  first  recur  to 
the  perfect  pollen-masses  of  the  male  Catasetum. 
These  may  be  seen  at  D  and  E,  fig.  29,  attached  to 
the  pedicel :  they  consist  of  a  large  sheet  of  cemented 
or  waxy  pollen-grains,  folded  over  so  as  to  form  a 
sack,  with  an  open  slit  along  the  lower  surface,  within 
which  at  the  lower  and  produced  end,  a  layer  of  highly 
elastic  tissue,  forming  the  caudicle,  is  attached;  the 
other  end  being  attached  to  the  pedicel  of  the  rostellum. 
The  exterior  grains  of  pollen  are  more  angular,  have 
thicker  walls,  and  are  yellower  than  the  interior  grains. 
In  the  early  bud  the  two  pollen-masses  are  enveloped 
in  two  conjoined  membranous  sacks,  which  are  soon 
penetrated  by  the  two  produced  ends  of  the  pollen- 
masses  and  by  their  caudicles ;  and  afterwards  the 
extremities  of  the  caudicles  adhere  to  the  pedicel. 
Before  the  flower  expands  the  membranous  sacks  in- 
cluding the  two  pollen-masses  open ;  and  the  pollen- 
masses  are  left  resting  naked  on  the  back  of  the 
rostellum. 

In  Monachanthus,  on  the  other  hand,  the  two  mem- 
branous sacks  containing  the  rudimentary  pollen- 
masses  never  open  ;  but  they  easily  separate  from  each 
other  and  from  the  anther.  The  tissue  of  which  they 
are  formed  is  thick  and  pulpy.  Like  most  rudi- 
mentary parts,  the  pollen-masses  vary  much  in  size 
and  form;  they  are  only  about  one-tenth  of  the  bulk 
of  those  of  the  male ;  they  are  flask-shaped  (p,  fig.  31), 
with  the  lower  end  greatly  produced  so  as  almost  to 
penetrate  the  exterior  or  membranous  sack.  There  is 
10 


202  VANDE.E.  Chap.  VII. 

no  fissare  along  their  lower  surfaces  for  the  protrusion 
of  the  caudicles.  The  exterior  pollen-grains  are  square 
and  have  thicker  walls  than  the  interior  grains,  just  as 
in  the  proper  male  pollen ;  and,  w^hat  is  very  curious, 
each  cell  has  its  nucleus.  Now,  E.  Brown  states*  that 
in  the  early  stages  of  the  formation  of  the  pollen-grains 
of  ordinary  Orchids  (as  with  other  plants)  a  minute 
nucleus  is  often  visible ;  so  that  the  rudimentary  pollen- 
grains  of  Monachanthus  apparently  have  retained — as 
is  so  general  with  rudiments  in  the  animal  kingdom — 
an  embryonic  character.  Lastly,  at  the  base,  within 
each  flask-shaped  pollen-mass,  there  is  a  little  mass  of 
brown  elastic  tissue, — that  is,  a  vestige  of  a  caudicle, — 
which  runs  far  up  the  pointed  end  of  the  flask,  but 
does  not  (at  least  in  some  of  the  specimens)  come  to 
the  surface,  and  could  never  be  attached  to  any  part  of 
the  pedicel.  These  rudimentary  and  enclosed  caudicles 
are,  therefore,  utterly  useless.  Notwithstanding  the 
small  size  and  almost  aborted  condition  of  the  female 
pollen-masses,  when  they  were  placed  by  Dr.  Criiger 
within  the  stigma  of  a  female  plant  they  emitted  "  here 
and  there  a  rudimentary  tube."  The  petals  then  faded 
and  the  ovarium  enlarged,  but  after  a  week  it  turned 
yellow  and  finally  dropped  off  without  bringing  any 
seeds  to  perfection.  This  appears  to  me  a  very  curious 
instance  of  the  slow  and  gradual  manner  in  which 
structures  are  modified  ;  for  the  female  pollen-masses, 
which  can  never  be  naturally  removed  or  applied  to 
the  stigma,  still  partially  retain  their  former  powers 
and  function. 

Thus  every  detail  of  structure  which  characterises 
the  male  pollen-masses  is  represented  in  the  female 
plant  in  a  useless  condition.    Such  cases  are  familiar  to 


♦  'Transactions  of  the  Linnean  Soc*  vol.  xvi,  p.  711. 


Chap.  VIL  MYANTHUS   BARBATUS.  203 

every  naturalist,  but  can  never  be  observed  without 
renewed  interest.  At  a  period  not  far  distant,  natura- 
lists will  hear  with  surprise,  perhaps  with  derision,  that 
grave  and  learned  men  formerly  maintained  that  such 
useless  organs  were  not  remnants  retained  by  inherit- 
ance, but  were  specially  created  and  arranged  in  their 
proper  places  like  dishes  on  a  table  (this  is  the  simile 
of  a  distinguished  botanist)  by  an  Omnipotent  hand 
"  to  complete  the  scheme  of  nature." 

The  third  form,  Myanthus  harhafus  (fig.  31,  B),  is 
sometimes  borne  on  the  same  plant  together  with  the 
two  preceding  forms.  The  flowers  differ  greatly  in 
external  appearance,  but  not  in  essential  structure, 
from  those  of  both  the  other  forms.  They  generally 
stand  in  a  reversed  position,  compared  with  those  of 
Catasetum  tridentatum  and  of  Monachanthus  viridis, 
that  is,  with  the  labellum  downwards.  The  labellum 
is  fringed  in  an  extraordinary  manner  with  long 
papillae ;  it  has  a  quite  insignificant  medial  cavity, 
at  the  hinder  margin  of  which  a  curious  curved  and 
flattened  horn  projects,  which  represents  the  anvil-like 
projection  on  the  labellum  of  the  male  G.  callosum. 
The  other  petals  and  sepals  are  spotted  and  elongated, 
with  the  two  lower  sepals  alone  reflexed.  The  antennae 
are  not  so  long  as  in  the  male  C.  tridentatum;  they 
project  symmetrically  on  each  side  of  the  horn-like 
process  at  the  base  of  the  labellum,  with  their  tips, 
which  are  not  roughened  with  papillae,  almost  entering 
the  medial  cavity.  The  stigmatic  chamber  is  of  nearly 
intermediate  size  between  that  of  the  male  and  female 
forms;  it  is  lined  with  utriculi  charged  with  brown 
matter.  The  straight  and  well-furrowed  ovarium  is 
nearly  twice  as  long  as  that  of  the  female  Monachan- 
thus, but  not  so  thick  where  it  joins  the  flower ;  the 
ovules  are  opaque  and  pulpy  after  having  been  kept 


204  VANDE.E.  Chap.  VIL 

in  spirits,  and  resemble  those  of  the  female  in  all 
respects,  but  are  not  so  numerous.  I  believe  that  I 
saw  the  nucleus  projecting  from  the  testa,  but  dare 
not,  as  in  the  case  of  the  Monachanthus,  speak  posi- 
tively. The  poUinia  are  about  a  quarter  of  the  size 
of  those  of  the  male  Catasetum,  but  have  a  perfectly 
well  developed  disc  and  pedicel.  The  pollen-masses 
were  lost  in  the  specimens  examined  by  me ;  but 
Mr.  Keiss  has  given,  in  the  Linnean  Transactions,  a 
drawing  of  them,  showing  that  they  are  of  due  pro- 
portional size  and  have  the  proper  folded  or  cleft 
structure,  within  which  the  caudicles  are  attached. 
Thus  as  both  the  male  and  female  organs  are  in 
appearance  perfect,  Mi/anthus  harhatus  may  be  con- 
sidered as  an  hermaphrodite  form  of  the  same  species, 
of  which  the  Catasetum  is  the  male  and  Monachan- 
thus the  female.  Nevertheless,  the  intermediate  forms, 
which  are  common  in  Trinidad,  and  which  resemble 
more  or  less  closely  the  above  described  Myanthus, 
have  never  been  seen  by  Dr.  Criiger  to  produce  seed- 
capsules. 

It  is  a  highly  remarkable  fact,  that  this  sterile 
hermaphrodite  form  resembles  in  its  whole  appearance 
and  structure  the  males  of  two  other  species,  namely, 
G.  saceatum  and  more  especially  G.  callosum,  much 
more  closely  than  it  does  either  the  male  or  female 
form  of  the  same  species.  As  all  orchids,  with  the 
exception  of  a  few  in  the  present  small  sub-family,  as 
well  as  all  the  members  of  several  allied  groups  of 
plants,  are  hermaphrodites,  there  can  be  no  doubt 
that  the  common  progenitor  of  the  Orchideae  was 
an  hermaphrodite.  We  may  therefore  attribute  the 
hermaphrodite  condition  and  the  general  appearance 
of  Myanthus  to  reversion  to  a  former  state;  and  if 
so,  the  ancestors  of  all  the  species  of  Catasetum  must 


Chap.  VII.  CATASETUM    TRIDENTATUM.  205 

have  resembled  the  males  of  G.  saccatum  and  callosumf 
for  as  we  have  just  seen,  it  is  to  these  two  plants  that 
Myanthus  presents  so  many  striking  resemblances.* 

Lastly  I  may  be  permitted  to  add  that  Dr.  Criiger, 
after  having  carefully  observed  these  three  forms  in 
Trinidad,  fully  admits  the  truth  of  my  conclusion  that 
Catasefum  tridentatum  is  the  male  and  Monaclianthus 
viridis  the  female  of  the  same  species.  He  further 
confirms  my  prediction  that  insects  are  attracted  to 
the  flowers  for  the  sake  of  gnawing  the  labellum,  and 
that  they  carry  the  pollen-masses  from  the  male  to  the 
female  plant.  He  says  "  the  male  flower  emits  a 
peculiar  smell  about  twenty -four  hours  after  opening, 
and  the  antennce  assume  their  greatest  irritability  at 
the  same  time.  A  large  humble-bee,  noisy  and  quarrel- 
some, is  now  attracted  to  the  flowers  by  the  smell, 
and  a  great  number  of  them  may  be  seen  every  morning 
for  a  few  hours  disputing  with  each  other  for  a  place  in 
the  interior  of  the  labellum,  for  the  purpose  of  gnawing 
off  the  cellular  tissue  on  the  side  opposite  to  the  column, 
so  that  they  turn  their  backs  to  the  latter.  As  soon  as 
they  touch  the  upper  antenna  of  the  male  flower,  the 
pollen-mass,  with  its  disc  and  gland,  is  fixed  on  their 
back,  and  they  arc  often  seen  flying  about  with  this 
peculiar-looking  ornament  on  them.  I  have  never 
seen  it  attached   except   to   the  very  middle  of  the 


♦  The  male  of  ihe  Indian  ante-  to  reversion  to  a  former  state  of 

\G^Ki(^A.bezoartica  after  castration  the   sptcies;    for   we   have   good 

produced  horns  of  a  widely  dit-  rea>oa  to  believe  that  any  cause 

ferent  shape   from   those   of  the  which    disturbs   the   constitution 

perfect    male;     find    larger    and  leads    to    reversion.      Myautlius, 

thicker    than    those   occasionally  though  having- the  organs  of  both 

produced  by  the  female.     We  see  sexes  apparently  perfect,  is  sterde; 

something  of  the  sanie  kind  in  the  it  has   ti  erelbre   had    its   sexual 

horns  of  the  common  ox.     I  have  constitution   disturbed,   and   this 

remarked  in  my  '  Descent  of  ]Man  '  seems  to  have  cause  d  it  to  revert 

(2nd    edit.    p.    50(j),    that    such  in  character  to  a  former  state, 
cases  may  probably  be  attributed 


206  VANDE^.  Chap.  VII. 

thorax.  When  the  bee  walks  about,  the  poUen-masa 
lies  flat  on  the  back  and  wings ;  but  when  the  insect 
enters  a  female  flower,  always  with  the  labellum  turned 
upwards,  the  pollinium,  which  is  hinged  to  the  gland 
by  elastic  tissue,  falls  back  by  its  own  weight  and  rests 
on  the  anterior  face  of  the  column.  When  the  insect 
returns  backwards  from  the  flower,  the  pollinia  are 
caught  by  the  upper  margin  of  the  stigmatic  cavity, 
which  projects  a  little  beyond  the  face  of  the  column ; 
and  if  the  gland  be  then  detached  from  the  back  of 
the  insect,  or  the  tissues  which  connect  the  pollinia 
with  the  caudicle,  or  this  with  the  gland,  break,  fecun- 
dation takes  place."  Dr.  Criiger  sent  me  specimens 
of  the  humble-bees  which  he  caught  gnawing  the 
labellum,  and  these  consist  of  Euglossa  nov.  spec,  ca- 
jennensis  and  piliventris. 

Cafasetum  mentosum  and  a  Monachanthus,  according 
to  Fritz  Miiller,*  grow  in  the  same  district  of  South 
Brazil  ;  and  he  easily  succeeded  in  fertilising  the 
latter  with  pollen  from  the  former.  The  pollen-masses 
could  be  inserted  only  partially  into  the  narrow 
stigmatic  cleft ;  but  when  this  was  done,  a  process  of 
deglutition,  as  described  under  Cirrh?ea,  commenced 
and  was  slowly  completed.  On  the  other  hand,  Fritz 
Miiller  entirely  failed  in  his  attempts  to  fertilise  the 
flowers  of  this  Catasetum  with  its  own  pollen  or  with 
that  from  another  plant.  The  pollinia  of  the  female 
Monachanthus  are  very  small ;  the  pollen-grains  are 
variable  both  in  size  and  shape ;  the  anther  never 
opens,  and  the  pollen-masses  are  not  attached  to 
the  caudicle.  Nevertheless,  when  these  rudimentary 
pollen-masses,  which  can  never  naturally  be  removed 
from  their  cells,  were   placed  on  the  slightly  viscid 


*  '  Bot.  Zcitnng,'  1868,  p.  630. 


Chap.  VII.  CATASETUM.  207 

stigma  of  the   male   Catasetum,  tliey   emitted   tlieir 
tubes. 

The  genus  Catasetum  is  interesting  to  an  unusual 
degree  in  several  respects.  The  separation  of  the 
sexes  is  unknown  amongst  other  Orchids,  except  per- 
haps in  the  allied  genus  Cycnoches.  In  Catasetum 
we  have  three  sexual  forms,  generally  borne  on  sepa- 
rate plants,  but  sometimes  mingled  together  on  the 
same  plant;  and  these  three  forms  are  wonderfully 
different  from  one  another,  much  more  different  than, 
for  instance,  a  peacock  is  from  a  peahen.  But  the 
appearance  of  these  three  forms  now  ceases  to  be  an 
anomaly,  and  can  no  longer  be  viewed  as  an  unparal- 
leled instance  of  variability. 

This  genus  is  still  more  interesting  in  its  manner  of 
fertilisation.  We  see  a  flower  patiently  waiting  with 
its  antennae  stretched  forth  in  a  well-adapted  position, 
ready  to  give  notice  whenever  an  insect  puts  its  head 
into  the  cavity  of  the  labellum.  The  female  Mona- 
chanthus,  not  having  true  pollinia  to  eject,  is  destitute 
of  antennae.  In  the  male  and  hermaphrodite  forms, 
namely  Catasetum  tridentatum  and  Myanthus  harhafus, 
the  pollinia  lie  doubled  up,  like  a  spring,  ready  to  be 
instantly  shot  forth  when  the  antennae  are  touched. 
The  disc  end  is  always  projected  foremost,  and  is  coated 
with  viscid  matter  which  quickly  sets  hard  and  affixes 
the  hinged  pedicel  firmly  to  the  insect's  body.  The 
insect  flies  from  flower  to  flower,  till  at  last  it  visits  a 
female  plant :  it  then  inserts  one  of  the  pollen-masses 
into  the  stigmatic  cavity.  As  soon  as  the  insect  flies 
away  the  elastic  caudicle,  made  weak  enough  to  yield 
to  the  viscidity  of  the  stigmatic  surface,  breaks,  and 
leaves  behind  a  pollen-mass  ;  then  the  pollen-tubes 
slowly  protrude,  penetrate  the  stigmatic  canal,  and  the 
act  of  fertilisation  is   completed.     Who   would  liave 


208  VANDE.E.  Chap.  VU 

been  bold  enough  to  have  surmised  that  the  propaga- 
tion of  a  species  depended  on  so  complex,  so  apparently 
artificial,  and  yet  so  admirable  an  arrangement  ? 

I  have  examined  three  other  genera  placed  by 
Lindley  in  the  small  sub-family  of  Catasetidse,  namely, 
Mormodes,  Cycnoches  and  Cyrtopodium.  The  latter 
plant  was  purchased  by  me  under  this  name,  and  bore 
a  flower-stem  about  four  feet  in  height  with  yellowish 
bracts  spotted  with  red  ;  but  the  flowers  presented 
none  of  the  remarkable  peculiaiities  of  the  three  other 
genera,  with  the  exception  that  the  anther  was  hinged 
to  a  point  projecting  from  the  summit  of  the  column, 
as  in  Catasetum. 

Mormodes  ignea. — To  show  how  difii cult  it  sometimes 
is  to  understand  the  manner  in  which  an  Orchid  is 
fertilised,  I  may  mention  that  I  carefully  examined 
twelve  flowers,*  trying  various  experiments  and  re- 
cording the  results,  before  I  could  at  all  make  out  the 
meaning  and  action  of  the  several  parts.  It  was  plain 
that  the  pollinia  were  ejected,  as  in  Catasetum,  but 
how  each  part  of  the  flower  played  its  proper  part  I 
could  not  even  conjecture.  I  had  given  up  the  case 
as  hopeless,  until  summing  up  my  observations,  the 
explanation  presently  to  be  given,  and  subsequently 
proved  by  repeated  experiments  to  be  correct,  suddenly 
occurred  to  me. 

The  flower  presents  an  extraordinary  appearance, 
and  its  mechanism  is  even  more  curious  than  its  ap- 
pearance (fig.  32).  The  base  of  the  column  is  bent 
backwards,  at  right  angles  to  the  ovarium  or  footstalk, 


♦    I   must  express   my  cordial  two  fine  spikes,  bearing  an  abun- 

thanks   to  Mr.  Kucker/of  West  dance  of  flowers,  and  for  having 

Hill,  Wandsworth,  lor  having  lent  allowed  me  to  keep  the  plant  for 

me  a  plant  of  this  Mormodes  with  a  considerable  time. 


Ohap.  VII. 


MORMODES  IGNEA< 


209 


and  then  resumes  an  upright  position  to  near  its 
summit,  where  it  is  again  bent.  It  is,  also,  twisted  in 
a  unique  manner,  so  that  its  front  surface,  including 


Fig.  32. 


MORMODES   IGNEA. 

Lateral  view  of  flower,  with  the  upper  sepal  and  the  near  upper  petal 
cut  off. 

N.B.  The  labellum  in  the  drawing  is  a  little  lifted  up,  to  show  the  de- 
pression on  Its  under  surface,  which  ought  to  be  pressed  close  down 
on  the  bent  summit  of  the  column. 


a.     anther. 

•pd.  pedicel  of  pollinium. 

s.      stigma. 


I.      labellum 
I.  s.   lateral 


the  anther,  rostellum,  and  the  upper  part  of  the  stigma 
faces  one  side  of  the  flower;  this  being  either  to  the 


210  VANDEiE.  Chap.  VII. 

right  or  left,  according  to  the  position  of  the  flower 
on  the  spike.  The  twisted  stigmatic  surface  extends 
down  to  the  base  of  the  column  and  is  hollowed  out 
into  a  deep  cavity  at  its  upper  end.  The  large  viscid 
disc  of  the  pollinium  is  lodged  in  this  cavity  close  be- 
neath the  rostellum ;  and  the  rostellum  is  seen  in  the 
drawing  (2^d.)  covered  by  the  bowed  pedicel. 

The  anther-case  (a  in  the  figure)  is  elongated  and 
triangular,  closely  resembling  that  of  Catasetum ;  but 
it  does  not  extend  up  to  the  apex  of  the  column.  The 
apex  consists  of  a  thin  flattened  filament,  which  from 
the  analogy  of  Catasetum  I  suppose  to  be  the  produced 
filament  of  the  stamen  ;  but  it  may  be  a  prolongation 
of  some  other  element  of  the  column.  In  the  bud- 
state  it  is  straight,  but  before  the  flower  expands,  it 
becomes  much  bent  by  the  pressure  of  the  labellum. 
A  group  of  spiral  vessels  runs  up  the  column  as  far  as 
the  summit  of  the  anther-case ;  they  are  then  reflexed 
and  run  some  way  down  the  anther-case.  The  point 
of  reflexion  forms  a  short  thin  hinge  by  which  the  top 
of  the  anther-case  is  articulated  to  the  column  beneath 
its  bent  summit.  The  hinge,  although  smaller  than  a 
pin's  head  in  size,  is  of  paramount  importance ;  for  it 
is  sensitive  and  conveys  the  stimulus  from  a  touch  to 
the  disc  of  the  pollinium,  causing  it  to  separate  from 
its  place  of  attachment.  The  hinge  also  serves  to 
guide  the  pollinium  during  its  ejection.  As  it  has 
to  convey  the  necessary  stimulus  to  the  disc,  one  may 
suspect  that  a  portion  of  the  rostellum,  which  lies  in 
close  contact  with  the  filament  of  the  anther,  runs  up 
to  this  point ;  but  I  could  not  here  detect  any  differ- 
ence in  structure  on  comparing  these  parts  with  those 
of  Catasetum.  The  cellular  tissue  round  the  hinge 
is  gorged  with  fluid,  and  a  large  drop  exudes  when 
the  anther  is  torn  from  the  column  during  the  ejection 


Chai-.  VII.  MORMODES   IGNEA.  211 

of  the  pollinium.  This  gorged  condition  may  perhaps 
facilitate  the  rupture  of  the  hinge. 

The  pollinium  does  not  differ  much  from  that  of 
Catasetnm  (see  fig.  29,  D,  p.  183);  and  it  lies  in  like 
manner  curved  round  the  rostellum,  which  is  less  protu- 
berant than  in  that  genus.  The  upper  and  broad  end  of 
the  pedicel,  however,  extends  beneath  the  pollen-masses 
within  the  anther ;  and  these  are  attached  by  rather 
weak  caudicles  to  a  medial  crest  on  its  upper  surface. 

The  viscid  surface  of  the  large  disc  lies  in  contact 
with  the  roof  of  the  stigmatic  cavity,  so  that  it  cannot 
be  touched  by  an  insect  visiting  the  flower.  The 
anterior  end  of  the  disc  is  furnished  with  a  small  de- 
pendent curtain  (dimly  shown  in  fig.  32) ;  and  this, 
before  the  act  of  ejection,  is  continuously  joined  on 
each  side  to  the  upper  margins  of  the  stigmatic  cavity. 
The  pedicel  is  united  to  the  posterior  end  of  the  disc  ; 
but  when  the  disc  is  freed,  the  lowermost  part  of  the 
pedicel  becomes  doubly  bent,  so  that  it  then  appears 
as  if  attached  by  a  hinge  to  the  centre  of  the  disc. 

The  labellum  is  a  highly  remarkable  structure :  it 
is  narrowed  at  its  base  into  a  nearly  cylindrical  foot- 
stalk, and  its  sides  are  so  much  reflexed  as  almost  to 
meet  at  the  back,  forming  a  folded  crest  on  the  sum- 
mit of  the  flower.  After  rising  up  perpendicularly 
it  arches  over  the  apex  of  the  column,  against  which  it 
is  firmly  pressed  down.  The  labellum  at  this  point  is 
hollowed  out  (even  in  the  bud)  into  a  slight  cavity, 
which  receives  the  bent  summit  of  the  column.  This 
slight  depression  manifestly  represents  the  large  cavity, 
with  thick  fleshy  walls,  which  insects  gnaw,  on  the 
anterior  surface  of  the  labellum  in  the  several  species 
of  Catasetum.  Here  by  a  singular  change  of  function, 
the  cavity  serves  to  keep  the  labellum  in  its  proper 
position  on  the  summit  of  the  column,  but  is,  perhaps, 


212  VANDE^.  Chap.  VU 

likewise  attractive  to  insects.  In  the  drawing  (fig.  32) 
tlie  labellum  has  been  forcibly  raised  a  little  up,  so  as 
to  show  the  depression  and  the  bent  filament.  In  its 
natural  position  it  may  almost  be  compared  to  a  huge 
cocked-hat,  supported  by  a  footstalk  and  placed  on  the 
head  of  the  column. 

The  twisting  of  the  column,  which  I  have  seen  in 
no  other  Orchid,  causes  all  the  important  organs  of 
fructification  in  the  flowers  on  the  left  side  of  the 
spike  to  face  to  the  left,  and  in  all  those  on  the  right 
side  to  face  to  the  right.  So  that  two  flowers  taken 
from  opposite  sides  of  the  same  spike  and  held  in 
the  same  relative  position  are  seen  to  be  twisted  in 
opposite  directions.  One  single  flower,  which  was 
crowded  by  the  others,  was  barely  twisted,  so  that  its 
column  faced  the  labellum.  The  labellum  is  also 
slightly  twisted  :  for  instance,  in  the  flower  figured, 
which  faced  to  the  left,  the  midrib  of  the  labellum  was 
first  twisted  to  the  right-hand,  and  then  to  the  left,  but 
in  a  less  degree,  and  being  bent  over  it  pressed  on  the 
posterior  surface  of  the  crooked  summit  of  the  column. 
The  twisting  of  all  the  parts  of  the  flower  commences 
in  the  bud. 

The  position  thus  acquired  by  the  several  organs  is 
of  the  highest  importance ;  for  if  the  column  and 
labellum  had  not  been  twisted  laterally,  the  pollinia, 
when  shot  forth,  would  have  struck  the  overarching 
labellum  and  have  then  rebounded,  as  actually  oc- 
curred with  the  single  abnormal  flower  having  a  nearly 
straight  column.  If  the  organs  had  not  been  twisted 
in  opposite  directions  on  the  opposite  sides  of  the  same 
crowded  spike,  so  as  always  to  face  to  the  outside,  there 
would  not  have  been  a  clear  space  for  the  ejection  of 
the  pollinia  and  their  adhesion  to  insects. 

When  the  flower  is  mature  the  three  sepals  hang 


Chap.  VII.  MORMODES   IGXEA.  213 

down,  but  the  two  upper  petals  remain  nearly  upright. 
The  bases  of  the  sepals,  and  especially  of  the  two 
upper  petals,  are  thick  and  swollen  and  have  a 
yellowish  tint ;  when  quite  mature,  they  are  so  gorged 
with  fluid,  that,  if  punctured  by  a  fine  glass  tube,  the 
fluid  rises  by  capillary  attraction  to  some  height  in  it. 
These  swollen  bases,  as  well  as  the  footstalk  of  the 
labellum,  have  a  decidedly  sweet  and  pleasant  taste ; 
and  I  can  hardly  doubt  that  they  are  attractive  to 
insects,  for  no  free  nectar  is  secreted. 

I  will  now  endeavour  to  show  how  all  the  parts  of 
the  flower  are  co-ordinated  and  act  together.  The 
pedicel  of  the  pollinium  is  bowed  round  the  rostellum, 
as  in  Catasetum;  in  this  latter  genus,  when  freed, 
it  merely  straightens  itself  with  force,  in  Mormodes 
something  more  takes  place.  If  the  reader  will  look 
forward  to  fig.  34  (p.  223),  he  will  see  a  section  of  the 
flower-bud  of  the  allied  genus  of  Cycnoches,  which 
difl'ers  only  in  the  shape  of  the  anther  and  in  the  viscid 
disc  having  a  much  deeper  dependent  curtain.  Now 
let  him  suppose  the  pedicel  of  the  pollinium  to  be  so 
elastic  that,  when  freed,  it  not  only  straightens  itself, 
but  suddenly  bends  back  on  itself  with  a  reversed 
curvature,  so  as  to  form  an  irregular  hoop.  The 
curved  surface  which  was  before  in  contact  with 
the  protuberant  rostellum  now  forms  the  outside 
of  the  hoop.  The  exterior  surface  of  the  curtain, 
which  depends  beneath  the  disc,  is  not  viscid;  and 
it  now  lies  on  the  anther-case,  with  the  viscid  surface 
of  the  disc  on  the  outside.  This  is  exactly  what  takes 
place  w'ith  Mormodes.  But  the  pollinium  assumes 
with  such  force  its  reversed  curvature  (aided,  appa- 
rently, by  a  transverse  curling  outwards  of  the  margins 
of  the  pedicel),  that  it  not  only  forms  itself  into  a 
hoop,  but  suddenly  springs  away  from  the  protuberant 


214  VANDExE.  Chap.  VII 

face  of  tlie  rostellum.  As  the  two  pollen-masses 
adhere,  at  first,  rather  firmly  to  the  anther-case,  the 
latter  is  torn  off  by  the  rebound  ;  and  as  the  thin 
hinge  at  the  summit  of  the  anther-case  does  not  yield 
so  easily  as  the  basal  margin,  the  pollinium  together 
with  the  anther-case  is  instantly  swung  upwards  like  a 
pendulum.  But  in  the  course  of  the  upward  swing 
the  hinge  yields,  and  the  whole  body  is  projected 
perpendicularly  up  in  the  air,  an  inch  or  two  above  and 
close  in  front  of  the  terminal  part  of  the  labellum.  If 
no  object  is  in  the  way,  as  the  pollinium  falls  down, 
it  generally  alights  and  sticks,  though  not  firmly,  on 
the  folded  crest  of  the  labellum,  directly  over  the 
column.  I  witnessed  repeatedly  all  that  has  been 
here  described. 

The  curtain  of  the  disc,  which,  after  the  pollinium 
has  formed  itself  into  a  hoop,  lies  on  the  anther-ca^e, 
is  of  considerable  service  in  preventing  the  viscid  edge 
of  the  disc  from  adhering  to  the  anther,  and  thus 
permanently  retaining  the  pollinium  in  the  form  of  a 
hoop.  This  would  have  been  fatal,  as  we  shall  pre- 
sently see,  to  a  subsequent  movement  of  the  pollinium 
which  is  necessary  for  the  fertilisation  of  the  flower. 
In  some  of  my  experiments,  when  the  free  action 
of  the  parts  was  checked,  this  did  occur,  and  the 
pollinium,  together  with  the  anther-case,  remained 
permanently  glued  together  in  the  shape  of  an  ir- 
regular hoop. 

I  have  already  stated  that  the  minute  hinge  by 
which  the  anther-case  is  articulated  to  the  column,  a 
little  w^ay  beneath  its  bent  filamentary  apex,  is  sen- 
sitive to  a  touch.  I  tried  four  times  and  found 
that  I  could  touch  with  some  force  any  other  part ; 
but  when  I  gently  touched  this  point  with  the  finest 
needle,  instantly  the  membrane  which  unites  the  disc 


Chap.  VII.  MORMODES   IGNEA.  215 

to  the  edges  of  the  stigmatic  cavity  where  it  is  lodged, 
ruptured,  and  the  pollinium  was  shot  upwards  and  fell 
on  the  crest  of  the  labellum  as  just  described. 

Now  let  us  suppose  an  insect  to  alight  on  the 
folded  crest  of  the  labellum,  and  no  other  convenient 
landing-place  is  afforded,  and  then  to  lean  over  the 
front  of  the  column  so  as  to  gnaw  or  suck  the  bases  of 
the  petals  swollen  with  sweet  fluid.  The  weight  and 
movements  of  the  insect  would  disturb  the  labellum 
and  the  bent  underlying  summit  of  the  column ;  and 
the  latter,  pressing  on  the  hinge  in  the  angle,  would 
cause  the  ejection  of  the  pollinium,  which  would  in- 
fallibly strike  the  head  of  the  insect  and  adhere  to 
it.  I  tried  by  placing  my  gloved  finger  on  the  summit 
of  the  labellum,  with  the  tip  just  projecting  beyond 
its  margin,  and  then  gently  moving  my  finger  it  was 
really  beautiful  to  see  how  instantly  the  pollinium 
was  projected  upwards,  and  how  accurately  the  viscid 
surface  of  the  disc  struck  my  finger  and  firmly 
adhered  to  it.  Nevertheless,  I  doubt  whether  the 
weight  and  movements  of  an  insect  would  suffice  to 
thus  act  indirectly  on  the  sensitive  point ;  but  look 
at  the  drawing  and  see  how  probable  it  is  that  an 
insect  leaning  over  would  place  its  front  legs  over  the 
edo:e  of  the  labellum  on  the  summit  of  the  anther- 
case,  and  thus  touch  the  sensitive  point.  The  pol- 
linium would  then  be  ejected,  and  the  viscid  disc 
would  certainly  strike  and  adhere  to  the  insect's  head. 

Before  proceeding,  it  may  be  worth  while  to  mention 
some  of  the  early  trials  which  I  made.  I  pricked 
deeply  the  column  in  different  parts,  including  the 
stigma,  and  cut  off  the  petals,  and  even  the  labellum, 
without  causing  the  ejection  of  the  pollinium ;  this, 
however,  once  happened  when  I  cut  rather  roughly 
through  the  thick  footstalk  of  the  labellum,  the  fila- 


216  YANDEX.  Chap.  VII 

mentaiy  summit  of  the  column  no  doubt  having  been 
thus  disturbed.  When  I  gently  prised  up  the  anther- 
case  at  its  base  or  on  one  side,  the  pollinium  was 
ejected,  but  then  the  sensitive  hinge  would  necessarily 
have  been  bent.  When  the  flower  has  long  remained 
expanded  and  is  nearly  ready  for  sj)ontaneous  ejection, 
a  slight  jar  on  any  part  of  the  flower  causes  the 
action.  Pressure  on  the  thin  pedicel  of  the  pollinium, 
and  therefore  on  the  underlying  protuberant  rostellum, 
is  followed  by  the  ejection  of  the  pollen-masses  ;  but 
this  is  not  surprising,  as  the  stimulus  from  a  touch 
on  the  sensitive  hinge  has  to  be  conveyed  through 
this  part  of  the  rostellum  to  the  disc.  In  Catasetum 
slight  pressure  on  this  point  does  not  cause  the  act 
of  ejection  ;  but  in  this  genus  the  protuberant  part  of 
the  rostellum  does  not  lie  in  the  course  along  which 
the  stimulus  has  to  be  conveyed  from  the  antennae 
to  the  disc.  A  drop  of  chloroform,  of  spirits  of  wine,  or 
of  boiling  water  placed  on  this  part  of  the  rostellum 
produced  no  effect ;  nor,  to  my  surprise,  did  exposure 
of  the  whole  flower  to  vapour  of  chloroform. 

Seeing  that  this  part  of  the  rostellum  was  sensitive 
to  pressure,  and  that  the  flower  was  widely  open  on 
one  side,  and  being  pre-occupied  with  the  case  of  Cata- 
setum, I  at  first  felt  convinced  that  insects  entered  the 
lower  part  of  the  flower  and  touched  the  rostellum. 
Accordingly  I  pressed  the  rostellum  with  variously- 
shaped  objects,  but  the  viscid  disc  never  once  adhered 
in  a  proper  manner  to  the  object.  If  I  used  a  thick 
needle,  the  pollinium,  when  ejected,  formed  a  hoop 
round  it  with  the  viscid  surface  outside ;  if  I  used  a 
broad  flat  object,  the  pollinium  struggled  against  it 
and  sometimes  coiled  itself  up  spirally,  but  the  disc 
either  did  not  adhere  at  all,  or  very  imperfectly.  At 
file  close  of  the  twelfth  trial  I  was  in  despair.     The 


Chap.  Vfl.  MOEMODES   IGNEA.  217 

strange  position  of  the  labellum,  perched  on  the  summit 
of  the  column,  ought  to  have  shown  me  that  here  was 
the  place  for  experiment.  I  ought  to  have  rejected 
the  notion  that  the  labellum  was  thus  placed  for  no 
good  purpose.  This  plain  guide  was  overlooked,  and 
for  a  long  time  I  completely  failed  to  understand  the 
structure  of  the  flower. 

We  have  seen  that  when  the  pollinium  is  ejected 
and  swings  upwards,  it  adheres  by  the  viscid  surface 
of  the  disc  to  any  object  projecting  beyond  the  edge 
of  the  labellum  directly  over  the  column.  When  thus 
attached,  it  forms  an  irregular  hoop,  with  the  torn-off 
anther-case  still  covering  the  pollen-masses  which  are 
close  to  the  disc,  but  protected  from  adhering  to  it 
by  the  dependent  curtain.  Whilst  in  this  position 
the  projecting  and  bowed  part  of  the  pedicel  would 
effectually  prevent  the  pollen-masses  from  being  placed 
on  the  stigma,  even  supposing  the  anther-case  to  have 
fallen  off.  Now  let  us  suppose  the  pollinium  to  be 
attached  to  an  insect's  head,  and  observe  what  takes 
place.  The  pedicel,  when  first  separated  from  the  ros- 
tellum,  is  damp;  as  it  dries,  it  slowly  straightens 
itself,  and  when  perfectly  straight  the  anther-case 
readily  drops  off.  The  pollen-masses  are  now  naked, 
and  they  are  attached  to  the  end  of  the  pedicel  by 
easily  ruptured  caudicles,  at  the  right  distance  and  in 
a  proper  position  for  their  insertion  into  the  adhesive 
stigma,  as  soon  as  the  insect  visits  another  flower. 
Thus  every  detail  of  structure  is  now  perfectly  adapted 
for  the  act  of  fertilisation. 

When  the  anther-case  drops  off,  it  has  performed  its 
triple  function  ;  namely,  its  hinge  as  an  organ  of  sense, 
its  weak  attachment  to  the  column  as  a  guide  causing 
the  pollinium  at  first  to  swing  perpendicularly  upwards, 
and  its  lower  margin,  together  with  the  curtain  of  the 


218  VANDE.E.  CiiAP.  VII 

disc,  as  a  protection  to  the  pollen-masses  from  being 
permanently  glued  to  the  viscid  disc. 

From  observations  made  on  fifteen  flowers,  it  was 
ascertained  that  the  straightening  of  the  pedicel  does 
not  occur  until  from  twelve  to  fifteen  minutes  have 
elapsed.  The  first  movement  causing  the  act  of  ejec- 
tion is  due  to  elasticity,  and  the  second  slow  movement 
to  the  drying  of  the  outer  and  convex  surface ;  but 
this  latter  movement  differs  from  that  observed  in  the 
poUinia  of  so  many  Vandeoe  and  Ophrese,  for,  when 
the  pollinium  of  this  Mormodes  was  placed  in  water, 
it  did  not  recover  the  hoop-like  form  which  it  had  at 
first  acquired  by  elasticity. 

The  flowers  are  hermaphrodites.  The  pollinia  are 
perfectly  developed.  The  elongated  stigmatic  surface 
is  extremely  viscid  and  abounds  with  innumerable 
utriculi,  the  contents  of  which  shrink  and  become 
.coagulated  after  immersion  for  less  than  an  hour  in 
spirits  of  wine.  When  placed  in  spirits  for  a  day,  the 
utriculi  were  so  acted  on  that  they  disappeared,  and  this 
I  have  not  noticed  in  any  other  Orchid.  The  ovules, 
after  exposure  to  spirits  for  a  day  or  two,  presented 
the  usual  semi-opaque,  pulpy  appearance  common  to 
all  hermaphrodite  and  female  Orchids.  From  the 
unusual  length  of  the  stigmatic  surface  I  expected 
that,  if  the  pollinia  were  not  ejected  from  the  excite- 
ment of  a  touch,  the  anther-case  would  have  detached 
itself,  and  the  pollen-masses  would  have  swung  down- 
wards and  fertilised  the  stigma  of  the  same  flower. 
Accordingly,  I  left  four  flowers  untouched  ;  after  they 
had  remained  expanded  from  eight  to  ten  days,  the 
elasticity  of  the  pedicel  conquered  the  force  of  attach- 
ment and  the  pollinia  were  spontaneously  ejected,  but 
they  did  not  fall  on  the  stigma  and  were  consequently 
Hasted. 


Chap  VII.  MOEMODES   LUXATA.  219 

Although  Mormodes  ignea  is  an  hermaphrodite,  yet 
it  must  be  as  truly  dioecious  in  function  as  Catasetum ; 
for  as  it  takes  from  twelve  to  fifteen  minutes  before 
the  pedicel  of  an  ejected  poUinium  straightens  itself 
and  the  anther-case  drops  off,  it  is  almost  certain  that 
within  this  time  an  insect  with  a  pollinium  attached 
to  its  head  would  have  left  one  plant  and  flown  to 
another. 

Mormodes  luxata. — This  rare  and  fine  species  is  ferti- 
lised in  the  same  manner  as  Mormodes  ignea,  but  differs 
in  several  important  points  of  structure.  The  right 
and  left  sides  of  the  same  flower  differ  from  one  another 
even  in  a  greater  degree  than  in  the  last  species.  One 
of  the  petals  and  one  of  the  sepals  project  at  right 
angles  to  the  column,  while  the  corresponding  ones 
stand  upright  and  surround  it.  The  upturned  and 
twisted  labellum  is  furnished  with  two  large  lateral 
lobes  :  of  these  one  embraces  the  column,  while  the 
other  stands  partly  open  on  the  side  where  the  one 
petal  and  sepal  lie  flat.  Insects  can  thus  easily  enter 
the  flower  on  this  latter  side.  All  the  flowers  on  the 
left  side  of  the  spike  are  open  on  their  left  sides,  while 
those  on  the  right  side  are  open  on  this  side.  The 
twisted  column  with  all  the  important  accessory  parts, 
together  with  the  rectangularly  bent  apex,  closely  re- 
semble the  corresponding  parts  in  M,  ignea.  But  the 
under  side  of  the  labellum  does  not  rest  on  and  press 
against  the  rectangularly  bent  apex  of  the  column. 
This  stands  free  in  the  middle  of  a  cup  formed  by  the 
extremity  of  the  labellum. 

I  did  not  obtain  many  flowers  fit  for  examination, 
as  three  had  ejected  their  pollinia  owing  to  the  shocks 
received  during  their  journey.  I  pricked  deeply  the 
labellum,  column  and  stigma  of  some  of  the  flowers 
without  any  effect ;  but  when  I  lightly  touched  with  a 


220  VANDEiE.  Chap.  VLL 

needle,  not  the  anther-Mnge  as  in  the  last  species,  but 
the  apex  of  the  column  of  one  flower,  the  pollinium 
was  instantly  ejected.  The  bases  of  the  petals  and 
sepals  are  not  swollen  and  succulent  like  those  of 
M.  ignea ;  and  I  have  little  doubt  that  insects  gnaw 
the  labellum,  which  is  thick  and  fleshy,  with  the  same 
peculiar  taste  as  in  Catasetum.  If  an  insect  were  to 
gnaw  the  terminal  cup,  it  could  hardly  fail  to  touch 
the  apex  of  the  column,  and  then  the  pollinium  would 
swing  upwards  and  adhere  to  some  part  of  the  insect's 
body.  The  pedicels  of  the  pollinia  straighten  them- 
selves and  the  anther-cases  are  cast  off,  in  about  fifteen 
minutes  after  the  act  of  ejection.  We  may  therefore 
confidently  believe  that  this  species  is  fertilised  in  the 
same  peculiar  manner  as  Mor modes  ignea. 

Cyciioches  ventricosum. — Mr.  Yeitch  was  so  kind  as  to 
send  me  on  two  occasions  several  flowers  and  flower- 
buds  of  this  extraordinary  plant.  A  sketch  of  a 
flower  in  its  natural  position,  with  one  sepal  cut  off, 
is  shown  at  fig.  33  (p.  222),  and  a  longitudinal  section 
through  a  young  bud  at  fig.  34  (p.  223). 

The  labellum  is  thick  and  fleshy,  wath  the  usual 
taste  of  this  organ  in  the  CatasetidDs  ;  it  resembles  in 
shape  a  shallow  basin  turned  upside  down.  The  two 
other  petals  and  the  three  sepals  are  reflexed.  The 
column  is  almost  cylindrical,  thin,  flexible,  elastic 
and  of  extraordinary  length.  It  curves  round  so 
as  to  bring  the  stigma  and  anther  opposite  to  and 
beneath  the  convex  surface  of  the  labellum.  The 
a23ex  of  the  column  is  not  nearly  so  much  produced  as 
in  Mormodes  and  Catasetum.  The  pollinia  closely 
resemble  those  of  Mormodes ;  but  the  disc  is  larger, 
and  its  curtain,  which  is  fringed,  is  so  large  that  it 
covers  the  whole  entrance  into  the  stigmatic  chamber. 
The  structure  of  these  parts  is  best  seen  in  the  section 


Chap.  VTI.  CYCNOCHES   VENTPJCOSUM.  221 

fig.  34 ;  in  which  the  pedicel  of  the  pollinium  has  not 
as  yet  become  separate  from  the  rostellum,  but  the 
future  line  of  separation  is  shown  by  a  line  (dotted 
in  the  figure)  of  hyaline  tissue.  The  filament  of  the 
anther  (/,  fig.  34)  has  not  as  yet  grown  to  its  full 
length.  When  fully  developed  it  bears  two  little  leaf- 
like appendages  which  lie  on  the  anther.  Lastly, 
on  the  sides  of  the  stigma  there  are  two  slight 
protuberances  (fig.  33),  which  apparently  represent 
the  antennae  of  Catasetum,  but  have  not  the  same 
function. 

Neither  the  labellum  nor  the  protuberances  on  the 
sides  of  the  stigma  are  at  all  sensitive  ;  but  when  on 
three  occasions  I  momentarily  touched  the  filament, 
between  the  little  leaf-like  appendages,  the  pollinium 
was  ejected  in  the  same  manner  and  through  the 
same  mechanism  as  in  Mormodes ;  but  it  was  thrown 
only  to  the  distance  of  about  an  inch.  If  the  filament 
had  been  touched  by  an  object  which  had  not  been 
quickly  removed,  or  if  by  an  insect,  the  viscid  disc 
would  certainly  have  adhered  to  it.  Mr.  Veitch  informs 
me  that  he  has  often  touched  the  end  of  the  column, 
and  the  pollinium  has  adhered  to  his  finger.  When 
the  pollinium  is  ejected,  the  pedicel  forms  a  hoop,  with 
the  exterior  surface  of  the  curtain  of  the  disc  resting 
on  and  covering  the  anther.  In  about  fifteen  minutes 
the  pedicel  straightens  itself,  and  the  anther-case 
drops  off ;  and  now  the  pollinium  is  in  a  right  position 
for  fertilising  another  flower.  As  soon  as  the  viscid 
matter  on  the  under  surface  of  the  disc  is  exposed  to 
the  air  it  quickly  changes  colour  and  sets  hard.  It 
then  adheres  with  surprising  force  to  any  object. 
From  these  various  facts  and  from  the  analogy  of  the 
other  Catasetidse,  we  may  conclude  that  insects  visit 
the  flowers   for  the  sake  of  gnawing  the  labellum  : 


222 


YANDEX. 


Chap.  YII. 


but  it  cannot  be  predicted  whether  they  alight  on  the 
surface  which  is  uppermost  in  the  drawing  (fig.  33)  and 


Fig.  33. 


Cycnoches  ventrhcosum. 
Flower  viewed  in  its  natural  dependent  position. 


c.  column,  after  the  ejection  of 
the  pollinium  together  with 
the  anther. 

/.      filament  of  anther. 


s.  stigmatic  cavity. 

L,  labellum. 

pet.  the  two  lateral  petals. 

j   sep.  sepals. 


then  crawl  over  the  margin  so  as  to  gnaw  the  convex 
surface,  and  in  doing  so  touch  with  their  abdomens 


Chap.  VII. 


CYCNOCHES   VENTRICOSUM. 


223 


the  extremity  of  the  column,  or  whether  they  first 
alight  on  this  part  of  the  column ;  but  in  either  case 
they  would  cause  the  ejection  of  the  pollinia,  which 
would  adhere  to  some  part  of  their  bodies. 
The  specimens   which  I   examined  Tvere  certainly 

Fig.  34. 


DlAQRAMMATIC  SECTION  OF  A  FlOWEE-BUD,   THE  COLUMN  PLACED 

UPRIGHT. 


d.  disc  of  polliQium  with  the  depen- 
dent curtain. 

s.    stigraatic  chamber. 

g.  stigmatic  canal  leading  to  the 
ovarium. 


a.     anther. 

/.     filament  of  anther. 

p.     pollen-mass. 

pd.  pedicel  of  pollinium,  barely  se- 
parated as  yet  from  the  ros- 
tellum. 

male  plants,  for  the  pollinia  were  well  developed.  The 
stigmatic  cavity  was  lined  with  a  thick  layer  of  pulpy 
matter  which  was  not  adhesive.  But  as  the  flowers 
cannot  possibly  be  fertilised  until  the  pollinia  have 
been  ejected,  together  with  the  great  curtain  which 
covers   the  whole   stigmatic  surface,  it   may  be  that 


224  VANDE^.  Chap.  VH. 

this  surface  becomes  j^t  a  later  period  adhesive  so  as  to 
secure  the  pollen-masses.  The  ovules  when  kept  for 
some  time  in  alcohol  were  filled  with  brownish  pulpy 
matter,  as  is  always  the  case  with  perfect  ovules. 
Therefore  it  appears  that  this  Cycnoches  must  be  an 
hermaphrodite  ;  and  Mr.  Bateman,  in  his  work  on  the 
Orchideae,  says  that  the  present  species  produces  seeds 
without  being,  as  I  understand,  artificially  fertilised  ; 
but  how  this  is  possible  is  unintelligible  to  me.  On 
the  other  hand.  Beer  says  *  that  the  stigma  of  Cyc- 
noches is  dry,  and  that  the  plant  never  sets  seeds. 
According  to  Lindley  C.  ventricosum  produces  on  the 
same  scape  flowers  with  a  simple  labellum,  others  with 
a  much  segmented  and  differently  coloured  labellum 
(viz.,  the  so-called  C.  egertonianum),  and  others  in  an 
intermediate  condition.  From  the  analogous  differ- 
ences in  the  flowers  of  Catasetum,  we  are  tempted  to 
believe  that  we  here  have  male,  female,  and  herma- 
phrodite forms  of  the  same  species  of  Cycnoches.  t 

I  have  now  finished  iny  description  of  the  CatasetidsB 
as  well  as  of  many  other  Vandese.  The  study  of  these 
wonderful  and  often  beautiful  productions,  with  all 
their  many  adaptations,  with  parts  capable  of  move- 
ment, and  other  parts  endowed  with  something  so  like, 
though  no  doubt  different  from,  sensibility,  has  been  to 
me  most  interesting.  The  flowers  of  Orchids,  in  their 
strange  and  endless  diversity  of  shape,  may  be  com- 


*  QiK.tedby  Irmisfh, 'Eeitrage  IMr.  Bateman   also   says   tlat  C. 

zur  Biologic  del- Orchideen,' 1853,  egertouiannm  lias  been  known  to 

p.  22.  produce  in  Guatemala  and  once 

t  Lindley's   *  Vegetable  King-  in  England    scapes   of  a  purplc- 

dom,'  1853,  p.  177.     He  has  also  floNvered  and  widely  different  spe- 

jmblished  in  the 'Botanical  I!egis-  cies  of  Cycnoches  ;    but   that   it 

ter,'  fol.  1951,  a  caso  of  two  forms  generally   produces    in    Eiigland 

appearing  on  the  same  scape   of  scapes  of  the  common  yellow  C, 

another     species     of    Cycnoches.  ventricosum. 


Chap.  VII.  VANDEiE.  225 

pared  with  the  great  vertebrate  class  of  Fish,  or  still 
more  appropriately  with  tropical  Homopterous  insects, 
which  appear  to  us  as  if  they  had  been  modelled 
in  the  wildest  caprice,  but  this  no  doubt  is  due  to 
our  ignorance  of  their  requirements  and  conditions 
of  life. 


11 


226  CYPEIFEDEiE.  OflAP.  VI II. 


CHAPTEE  VIII. 

CYPRIPEDE.E— HOMOLOGIES   OF   THE   FLOWERS   OF 
OECHIDS. 

Cypripedium,  differs  much  from  all  other  Orchids — ^Labellum  in  the 
form  of  a  slipper  with  two  small  orifices  by  which  insects  can  escape 
— Manner  of  fertilisation  by  small  bees  of  the  genns  Andrena — 
Homological  nature  of  the  several  parts  of  the  flowers  of  the  Orchidese 
— Wonderful  amount  of  modification  which  they  have  undergone. 

We  have  now  arrived  at  Lindley's  last  and  seventh 
tribe,  including,  according  to  most  botanists,  only  a 
single  genus,  Cypripedium,  which  differs  from  all 
other  Orchids  far  more  than  any  other  two  of  these 
do  from  one  another.  An  enormous  amount  of  ex- 
tinction must  have  swept  away  a  multitude  of  inter- 
mediate forms,  and  has  left  this  single  genus,  now 
widely  distributed,  as  a  record  of  a  former  and  more 
simple  state  of  the  great  Orchidean  Order.  Cypripe- 
dium possesses  no  rostellum ;  for  all  three  stigmas 
are  fully  developed,  though  confluent.  The  single 
anther,  which  is  present  in  all  other  Orchids,  is  here 
rudimentary,  and  is  represented  by  a  singular  shield- 
like projecting  body,  deeply  notched  or  hollowed  out 
on  its  lower  margin.  There  are  two  fertile  anthers 
which  belong  to  an  inner  whorl,  represented  in  ordinary 
Orchids  by  various  rudiments.  The  grains  of  pollen 
are  not  united  together  by  threes  or  fours,  as  in  so 
many  other  genera,  nor  are  they  tied  together  by 
elastic  threads,  nor  furnished  with  a  caudicle,  nor 
cemented    into   waxy   masses.     The    label lum    is    of 


Chat.  VIII. 


CYPRIPEDIUM. 


227 


large  size,  and  is  a  compound  organ  as  in  all  other 
Orchids. 

The  following  remarks  apply  only  to  the  six  species 
which  I  have  examined,  namely,  G,  harhatum,  purpu- 
ratuniy  insigne,  venustum,  piibescens  and  acaule  ;  though 
I  have  casually  looked  at  some  other  kinds.  The 
basal  part  of  the  labellum  is  folded  round  the  short 

Fig.  35. 


Cypripedium. 


a.    anther. 

a',  rudimentary,  shield-like  anther, 

s.    stigma. 

/,    labellum. 

A.  Flower  viewed  from  above,  with 
the  sepals  and  petals,  excepting 
the  labellum,  partly  cut  off". 
The  labellum  has  been  slightly 
depressed,   so  that   the   dorsal 


surface  of  the  stigma  is  ex- 
posed ;  the  edges  of  the  label- 
lum have  thus  become  a  little 
separated  and  the  toe  or  ex- 
tremity stands  lower  than  is 
natural. 
Side  view  of  column,  with  all 
the  sepals  and  petals  removed. 


column,  so  that  its  edges  nearly  meet  along  the  dorsal 
surface  ;  and  the  broad  extremity  is  folded  over  in  a 
peculiar  manner,  forming  a  sort  of  shoe,  which  closes 
up  the  end  of  the  flower.  Hence  arises  the  English 
name  of  Ladies'-slipper.  The  overarching  edges  of  the 
labellum  are  inflected  or  sometimes  only  suiootli  and 


228  CYPKIPEDE^.  Chap.  VIU 

polished  internally ;  and  this  is  of  much  importance, 
as  it  prevents  insects  which  have  once  entered  the 
labellum  from  escaping  through  the  great  opening  in 
the  upper  surface.  In  the  position  in  which  the  flower 
grows,  as  here  represented,  the  dorsal  surface  of  the 
column  is  uppermost.  The  stigmatic  surface  is  slightly- 
protuberant,  and  is  not  adhesive;  it  stands  nearly 
parallel  to  the  lower  surface  of  the  labellum.  With  a 
flower  in  its  natural  state,  the  margin  of  the  dorsal 
surface  of  the  stigma  can  be  barely  distinguished  be- 
tween the  edges  of  the  labellum  and  through  the 
notch  in  the  rudimentary,  shield-like  anther  (a')  ;  but 
in  the  drawing  (s,  fig.  A)  the  margin  of  the  stigma  has 
been  brought  outside  the  edges  of  the  depressed  la- 
bellum, and  the  toe  is  a  little  bent  downwards,  so  that 
the  flower  is  represented  as  rather  more  open  than  it 
really  is.  The  edges  of  the  pollen-masses  of  the  two 
lateral  anthers  (a)  can  be  seen  through  the  two  small 
orifices  or  open  spaces  in  the  labellum  (fig.  A)  on 
each  side,  close  to  the  column.  These  two  orifices  are 
essential  for  the  fertilisation  of  the  flower. 

The  grains  of  pollen  are  coated  by  and  immersed  in 
viscid  fluid,  which  is  so  glutinous  that  it  can  be  drawn 
out  into  short  threads.  As  the  two  anthers  stand  be- 
hind and  above  the  lower  convex  surface  (see  fig.  B)  of 
the  stigma,  it  is  impossible  that  the  glutinous  pollen 
can  without  some  mechanical  aid  get  on  to  this,  the 
efficient  surface  of  the  stigma.  The  economy  here 
shown  by  Nature  in  her  manner  of  gaining  the  same 
end  is  surprising.  In  all  the  other  Orchids  seen  by 
me,  the  stigma  is  viscid  and  more  or  less  concave,  by 
which  means  the  dry  pollen,  transported  by  means  of 
the  viscid  matter  secreted  by  the  rostellum  or  modified 
stigma,  is  retained.  In  Cypripedium  the  pollen  is 
glutinous,  and  assumes  the  function  of  viscidity,  which 


Chap.  Vin.  CYPRIPEDIUM.  229 

in  all  other  Orchids  except  Vanilla  belongs  exclusively 
to  the  rostellum  and  the  two  confluent  stigmas.  These 
latter  organs,  on  the  other  hand,  in  Cypripedium  en- 
tirely lose  their  viscidity,  and  at  the  same  time  become 
slightly  convex,  so  as  more  effectually  to  rub  off  the 
glutinous  pollen  adhering  to  the  body  of  an  insect. 
Moreover  in  several  of  the  North  American  species, 
as  in  G.  acaule  and  imhescens,  the  surface  of  the  stigma 
is  beset,  as  Professor  Asa  Gray  remarks,  *  "  with 
minute,  rigid,  sharp-pointed  papillae,  all  directed  for- 
wards, which  are  excellently  adapted  to  brush  off  the 
pollen  from  an  insect's  head  or  back."  There  is  one 
partial  exception  to  the  above  .rule  of  the  pollen  of 
Cypripedium  being  viscid  while  the  stigma  is  not 
viscid  and  is  not  convex ;  for  in  G.  acaule  the  pollen 
is  more  granular  and  less  viscid,  according  to  Asa 
Gray,  than  in  the  other  American  species,  and  in 
G.  acaule  alone  the  stigma  is  slightly  concave  and 
viscid.  So  that  here  the  exception  almost  proves  the 
truth  of  the  general  rule. 

I  have  never  been  able  to  detect  nectar  within  the 
labellum,  and  Kurrj  makes  the  same  remark  with 
respect  to  G.  calceolus.  The  inner  surface  of  the  la- 
bellum, however,  in  those  species  which  I  examined, 
is  clothed  with  hairs,  the  tips  of  which  secrete  little 
drops  of  slightly  viscid  fluid.  And  these  if  sweet  or 
nutritious  would  suffice  to  attract  insects.  The  fluid 
when  dried  forms  a  brittle  crust  on  the  summits  of  the 
hairs.  Whatever  the  attraction  may  be,  it  is  certain 
that  small  bees  frequently  enter  the  labellum. 

Formerly  I  supposed  that  insects  alighted  on  the 
labellum  and  inserted  their  proboscides  through  either 


* 'American  Journal  of  Science,'  t  'Bedeutung     der  Ncktnrien^ 

vol.  xxxiv.  18G2,  p.  428.  1838,  p.  29. 


230  CYPRIPEDE^.  Chap.  VIIL 

of  the  orifices  close  to  the  anthers ;  for  I  found  that 
when  a  bristle  was  thus  inserted  the  glutinous  pollen 
adhered  to  it,  and  could  afterwards  be  left  on  the 
stigma ;  but  this  latter  part  of  the  operation  was  not 
well  effected.  After  the  publication  of  my  book 
Professor  Asa  Gray  wrote  to  me  *  that  he  was  convinced 
from  an  examination  of  several  American  species  that 
the  flowers  were  fertilised  by  small  insects  entering  the 
labellum  through  the  large  opening  on  the  upper  sur- 
face, and  crawling  out  by  one  of  the  two  small  orifices 
close  to  the  anthers  and  stigma.  Accordingly  I  first 
introduced  some  flies  into  the  labellum  of  G.  puhescens, 
through  the  large  upper  opening,  but  they  were  either 
too  large  or  too  stupid,  and  did  not  crawl  out  properly. 
T  then  caught  and  placed  within  the  labellum  a  very 
small  bee  which  seemed  of  about  the  right  size,  namely, 
Andrena  ])arvula,  and  this  by  a  strange  chance  proved, 
as  we  shall  presently  see,  to  belong  to  the  genus  on 
v/hich  in  a  state  of  nature  the  fertilisation  of  C.  calceo- 
lus  depends.  The  bee  vainly  endeavoured  to  crawl  out 
again  the  same  way  by  which  it  had  entered,  but  always 
fell  backwards,  owing  to  the  margins  being  inflected. 
The  labellum  thus  acts  like  one  of  those  conical  traps 
with  the  edges  turned  inwards,  which  are  sold  to  catch 
beetles  and  cockroaches  in  the  London  kitchens.  It 
could  not  creep  out  through  the  slit  between  the  folded 
edges  of  the  basal  part  of  the  labellum,  as  the  elongated, 
triangular,  rudimentary  stamen  here  closes  the  passage. 
Ultimately  it  forced  its  way  out  through  one  of  the 
small  orifices  close  to  one  of  the  anthers,  and  was 
found  when  caught  to  be  smeared  with  the  glutinous 
pollen.  I  then  put  the  same  bee  back  into  the  label- 
lum ;  and  again  it  crawled  out  through  one  of  the  small 


*  See  also  '  Aiucrican  Journal  of  Science,'  vol.  xxxiv.  18G2,  p.  427. 


Chap.  VIII.  CYPEIPEDIUM.  231 

orifices,  always  covered  with  pollen.  I  repeated  the 
operation  five  times,  always  with  the  same  result.  I 
afterwards  cut  away  the  labellum,  so  as  to  examine  the 
stigma,  and  found  its  whole  surface  covered  with  pollen. 
It  should  be  noticed  that  an  insect  in  making  its  escape 
must  first  brush  past  the  stigma  and  afterwards  one  of 
the  anthers,  so  that  it  cannot  leave  pollen  on  the 
stigma,  until  being  already  smeared  with  pollen  from 
one  flower  it  enters  another ;  and  thus  there  will  be  a 
good  chance  of  cross-fertilisation  between  two  distinct 
plants.  Delpino*  with  much  sagacity  foresaw  that 
some  insect  would  be  discovered  to  act  in  this  manner ; 
for  he  argued  that  if  an  insect  were  to  insert  its  pro- 
boscis, as  I  had  supposed,  from  the  outside  through 
one  of  the  small  orifices  close  to  one  of  the  anthers,  the 
stigma  would  be  liable  to  be  fertilised  by  the  plant's 
own  pollen :  and  in  this  he  did  not  believe,  from 
having  confidence  in  what  I  have  often  insisted  on — 
namely,  that  all  the  contrivances  for  fertilisation  are 
arranged  so  that  the  stigma  shall  receive  pollen  from 
a  distinct  flower  or  plant.  But  these  speculations  are 
now  all  superfluous ;  for,  owing  to  the  admirable  ob- 
servations of  Dr.  H.  Miiller,  t  we  know  that  Cijpvi- 
'pedium  caleeolus  in  a  state  of  nature  is  fertilised  in  the 
manner  just  described  by  bees  belonging  to  five  species 
of  Andrena. 

Thus  the  use  of  all  the  parts  of  the  flower, — namely, 
the  inflected  edges,  or  the  polished  inner  sides  of  the 
labellum, — the  two  orifices  and  their  position  close  to 
the  anthers  and  stigma, — the  large  size  of  the  medial 
rudimentary  stamen, — are  rendered  intelligible.      An 


*   '  Fecondazione  ndle  Piante  xxv.  III.  Folge,  v.  Bd.  p.  1 :  see 

Antocarpee,'  1867,  p.  20.  also    '  Bcfruclituug  der  BJumcu/ 

t  'Yerh.  d.  Nat.  Ver.  fur  Pr.  1873,  p.  76. 
Kheinland   und  Wcstfal '  Jakrg. 


232  HOMOLOGIES   OF   THE  Chap.  Till 

msect  which  enters  the  labellum  is  thus  compelled  to 
crawl  out  by  one  of  the  two  narrow  passages,  on  the 
sides  of  which  the  pollen-masses  and  stigma  are  placed. 
We  have  seen  that  exactly  the  same  end  is  gained  in 
the  case  of  Coryanthes  by  the  labellum  being  half- 
filled  with  secreted  fluid ;  and  in  the  case  of  Pterostylis 
and  some  other  Australian  Orchids  by  the  labellum 
being  irritable,  so  that  when  touched  by  an  entering 
insect  it  shuts  up  the  flower,  with  the  exception  of  a 
single  narrow  passage.* 

Homological  Nature  of  the  several  Farts  of  the  Flowers  of 
the  Orchidese. 

The  theoretical  structure  of  few  flowers  has  been  so 
largely  discussed  as  that  of  the  Orchidese ;  nor  is  this 
surprising,  seeing  how  unlike  they  are  to  common 
flowers ;  and  here  will  be  a  convenient  place  for  con- 
sidering this  subject.  No  group  of  organic  beings  can 
be  well  understood  until  their  homologies  are  made 
out ;  that  is,  until  the  general  pattern,  or,  as  it  has 
often  been  called,  the  ideal  type,  of  the  several  mem- 
bers of  the  group  is  intelligible.  No  one  member 
may  now  exist  exhibiting  the  full  pattern ;  but  this 
does  not  make  the  subject  less  important  to  the  natu- 
ralist,— probably  makes  it  more  important  for  the 
full  understanding  of  the  group. 

The  homologies  of  any  being,  or  group  of  beings. 


*  Selenipedium  palmifolium  is  tlie  fish-pot  system,  i.  e.  a  funnel- 

oue     of    the     Cypripedese,    and  shaped  opening  conducts  into  it, 

according  to  Dr.  Criiger  (' Journ.  and    insects    find  it  difficult  to 

Linn.  Soc.  Bot.'  vol.  viii.  1864,  p.  escape  through  the  same.     The 

]  84)  bears  very  fragrant  flowers,  only  other  opening  near  the  base 

which    "in    all    probability   are  of  tlie  labellum  is  partly  closed 

always  impregnated  by  insects.  by  the  sexual  apparatus,  and  the 

The  labellum  is,  like  some  Aris-  insect  has   to  force  its  way  out 

tolochia-flowers,  constructi  d  after  there." 


Chap.  VIII.  FLOWERS   OF   ORCHIDS.  233 

can  be  most  surely  made  out  by  tracing  their  embryo- 
logical  development  wlien  that  is  possible ;  or  by  the 
discovery  of  organs  in  a  rudimentary  condition  ;  or  by 
tracing,  through  a  long  series  of  beings,  a  close  gradation 
from  one  part  to  another,  until  the  two  parts  or  organs, 
though  employed  for  widely  different  functions  and 
most  unlike  each  other,  can  be  joined  by  a  succession 
of  short  links.  No  instance  is  known  of  a  close  gradation 
between  two  organs,  unless  they  are  homologically  one 
and  the  same  organ. 

The  importance  of  the  science  of  Homology  rests  on 
its  giving  us  the  key-note  of  the  possible  amount  of 
difference  in  plan  within  any  group  ;  it  allows  us  to 
class  under  proper  heads  the  most  diversified  organs  ; 
it  shows  us  gradations  which  would  otherwise  have 
been  overlooked,  and  thus  aids  us  in  classification ;  it . 
explains  many  monstrosities ;  it  leads  to  the  detection 
of  obscure  and  hidden  parts,  or  mere  vestiges  of  parts, 
and  shows  us  the  meaning  of  rudiments.  Besides 
these  uses.  Homology  clears  away  the  mist  from  such 
terms  as  the  scheme  of  nature,  ideal  types,  archetypal 
patterns  or  ideas,  &c. ;  for  these  terms  come  to  express 
real  facts.  The  naturalist,  thus  guided,  sees  that  all 
homologous  parts  or  organs,  however  much  they  may 
be  diversified,  are  modifications  of  one  and  the  same 
ancestral  organ ;  in  tracing  existing  gradations  he 
gains  a  clue  in  tracing,  as  far  as  that  is  possible,  the 
probable  course  of  modification  through  which  beings 
have  passed  during  a  long  line  of  generations.  He 
may  feel  assured  that,  whether  he  follows  embryo- 
logical  development,  or  searches  for  the  merest  rudi- 
ment, or  traces  gradations  between  the  most  different 
beings,  he  is  pursuing  the  same  object  by  different 
routes,  and  is  tending  towards  the  knowledge  of  the 
actual  progenitor  of  the  group,  as  it  once  grew  and 


234  HOMOLOGIES  OF  THE  Chap.  VIII. 

lived.     Thus  the  subject  of  Homology  gains  largely 
in  interest. 

Although  this  subject,  under  whatever  aspect  it  be 
viewed,  will  always  be  most  interesting  to  the  student 
of  nature,  it  is  very  doubtful  whether  the  following 
details  on  the  homological  nature  of  the  flowers  of 
Orchids  will  possess  any  interest  for  the  general  reader. 
If,  indeed,  he  cares  to  see  how  much  light  an  acquaint- 
ance with  homology,  though  far  from  perfect,  throws 
on  a  subject,  this  will,  perhaps,  be  nearly  as  good  an 
instance  as  could  be  given.  He  will  see  how  curiously 
a  flower  may  be  moulded  out  of  many  separate  organs, 
— how  perfect  the  cohesion  of  primordially  distinct 
parts  may  become, — how  organs  may  be  used  for  pur- 
poses widely  different  from  their  proper  uses, — how 
other  organs  may  be  entirely  suppressed,  or  leave  mere 
useless  emblems  of  their  former  existence.  Finally, 
he  will  see  how  enormous  has  been  the  amount  of 
change  which  these  flowers  have  undergone  from  their 
parental  or  typical  form. 

Kobert  Brown  first  clearly  discussed  the  homologies 
of  Orchids,*  and  left,  as  might  be  expected,  little  to 
be  done.  Guided  by  the  general  structure  of  mono- 
cotyledonous  plants  and  by  various  considerations, 
he  propounded  the  doctrine  that  the  flower  properly 
consists  of  three  sepals,  three  petals,  six  anthers  in 
two  whorls  or  circles  (of  which  only  one  anther  belong- 
ing to  the  outer  whorl  is  perfect  in  all  the  common 
forms),  and  of  three  pistils,  with  one  of  them  modified 
into  the  rostellum.  These  fifteen  organs  are  arranged 
as  usual,  alternately,  three  within  three,  in  five  whorls. 
Of    the   existence  of  three  of  the  anthers  in  two  of 


*  I  believe  his  latest  views  are       the  '  Linnean  Transactions,'  vol. 
given  in  his  celebrated  paper,  read       xvi.  p.  GSo. 
Nov.  1-15, 18:51,  and  imblished  in 


Dhap.  VIII.  FLOWJTES   OF   OKCHIDS.  235 

the  whorls,  K.  Brown  offers  no  sufficient  evidence,  but 
believes  that  they  are  combined  with  the  labellum, 
whenever  that  organ  presents  crests  or  ridges.  In 
these  views  Brown  is  followed  by  Lindley.* 

Brown  traced  the  spiral  vessels  in  the  flower  by 
making  transverse  sections,  f  and  only  occasionally,  as 
far  as  it  appears,  by  longitudinal  sections.  As  spiral 
vessels  are  developed  at  a  very  early  period  of  growth, 
and  this  circumstance  always  gives  much  value  to  a 
part  in  making  out  homologies ;  and  as  they  are  ap- 
parently of  high  functional  importance,  though  their 
function  is  not  well  known,  it  appeared  to  me,  guided 
also  by  the  advice  of  Dr.  Hooker,  to  be  worth  while  to 
trace  upwards  all  the  spiral  vessels  from  the  six  groups 
surrounding  the  ovarium.  Of  the  six  ovarian  groups 
of  vessels,  I  will  call  (though  not  correctly)  that  under 
the  labellum  the  anterior  group ;  that  under  the 
upper  sepal  the  posterior  group  ;  and  the  two  groups 
on  the  two  sides  of  the  ovarium  the  antero-lateral  and 
postero-lateral  groups. 

The  result  of  my  dissections  is  given  in  the  following 
diagram  (fig.  36).     The  fifteen  little  circles  represent 


*  Professor  Asa  Gray  has  de-  the  union  of  one  petal  with  two 

scribed  in  the  '  American  Journal  petaloid  stamens, 

of  Science,'  July  1866,  a  monstrous  f  '  Linn.  Transact.'  vol.  xvi.  p. 

flower  of  Ci/pripedium  candidum,  696-701.     Link   in   liis   '  Bemer- 

and  remarks  on  it,  "  here  we  have  kungen  Uber  der  Ban  der  Orchi- 

(and    perhaps    the    iirst    direct)  deen'('BotanischeZeitung,' 1849, 

demonstration  that  the  orchideous  p.  745)  seems  to  have  also  trustt  d 

type  of  flower  has  two  staminal  to   transverse   sections.     Had  he 

verticils,   as    Brown    always    in-  traced  the  vessels  upwards  I  can- 

si.sted.''    Dr.  Criiger  also  advances  not  believe  that  he  would  have 

evidence    ( '  Journ.     Linn.     Soc.  disputed    Brown's    view    of    the 

Bot.'   vol.  viii.  1861,  p.   132)  in  nature    of    the    two    anthers    in 

favour    of    the   presence   of    five  Cypripedium.     Brongniart  in  liia 

whorls  of  organs  ;   but  he  denies  admirable    paper   ('  Annales   des 

that  the  homologies  of  the  parts  Sciences  Nat.'   torn.   xxiv.    1831 1 

can  be  deduced  from  the  course  of  incidentally  shows  tlio  course  of 

the  vessLils,  and  lie  does  not  admit  some  of  the  spiral  vessels, 
that   the   labfllum  is  formed  by 


236 


HOMOLOGIES   OF   THE 


CUAP.  VIII 


SO  many  groups  of  spiral  vessels,  in  every  case  traced 
down  to  one  of  the  six  large  ovarian  groups.  They 
alternate  in  five  whorls,  as  represented  ;  but  I  have  not 
attempted  to  give  the  actual  distances  at  which  they 
stand  apart.  In  order  to  guide  the  eye,  the  three 
central  groups  running  to  the  three  pistils  are  con- 
nected by  a  triangle. 

Fig.  36. 
Upper  or  posterior  sepal. 


Upper  ^ 
petal. 


Upper 
petal. 


Labellum. 

Section  of  the  Flower  of  an  Orchid. 

The  little  circles  show  the  position  of  the  spiral  vessels. 


Ai 


SS.  Stigmas;  Sr,  stigma  modified 
into  the  rostellum. 
Fertile  anther  of  the  outer 
whorl ;  Ag  A3,  anthers  of  the 
same  whorl  combined  with 
the  lower  petal,  forming  the 
labellum. 


flj  Gj.  Rudimentary  anthers  of  the 
inner  whorl  (fertile  in  Cypri- 
pedium),  generally  forming 
the  clinandrum  ;  Oj,  third 
anther  of  the  same  whorl, 
when  present,  forming  the 
front  of  the  column. 


Five  groups  of   vessels  run  into  the  three  sepals 
together  with  the  two  upper  petals ;  three  enter  the 


CiiAP.  VIII.  FLOWEKS   OF   OECHIDS.  237 

labellum  ;  and  seven  run  up  the  great  central  column. 
These  vessels  are  arranged,  as  may  be  seen,  in  rays 
proceeding  from  the  axis  of  the  flower ;  and  all  on  the 
same  ray  invariably  run  into  the  same  ovarian  group  ; 
thus  the  vessels  supplying  the  upper  sepal,  the  fertile 
anther  (Ai),  and  the  upper  pistil  or  stigma  (i.  e.  the 
rostellum  S^),  all  unite  and  form  the  posterior  ovarian 
group.  Again,  the  vessels  supplying,  for  instance,  the 
left  lower  sepals,  the  corner  of  the  labellum  and  one 
of  the  two  stigmas  (S)  on  the  same  side,  unite  and  form 
the  antero-lateral  group;  and  so  with  all  the  other 
vessels. 

Hence,  if  the  existence  of  groups  of  spiral  vessels 
can  be  trusted,  the  flower  of  an  Orchid  certainly 
consists  of  fifteen  organs,  in  a  much  modified  and 
confluent  condition.  We  see  three  stigmas,  with  the 
two  lower  ones  generally  confluent,  and  with  the  upper 
one  modified  into  the  rostellum.  We  see  six  stamens, 
arranged  in  two  whorls,  with  generally  one  alone  (Ai) 
fertile.  In  Cypripedium,  however,  two  stamens  of 
the  inner  whorl  {a^  and  a^  are  fertile,  and  in  other 
Orchids  these  two  are  represented  more  plainly  in 
various  ways  than  the  remaining  stamens.  The  third 
stamen  of  the  inner  whorl  (^3),  when  its  vessels  can 
be  traced,  forms  the  front  of  the  column :  Brown 
thought  that  it  often  formed  a  medial  excrescence, 
or  ridge,  cohering  to  the  labellum  ;  or,  in  the  case  of 
G-lossodia,*  a  filamentous  organ,  freely  projecting  in 
front  of  the  labellum.  The  former  conclusion  does 
not  agree  with  my  dissections;  about  Glossodia  I 
know  nothing.  The  two  infertile  stamens  of  the  outer 
whorl  (A2,  A3)  were  believed  by  Brown  to  be  only 
occasionally  represented,  and  then  by  lateral   excre- 

*  See  Brown's  obsevvatioTis  'Plautte  Asiaticse  rarioies/  1830, 
■under    Apoatabia    in     Wallicb'a       p.  74. 


238  HOMOLOGIES   OF   THE  Chap.  VIII. 

scences  on  tlie  labellum  ;  but  I  find  the  corresponding 
vessels  invariably  present  in  the  labellum  of  every 
Orchid  examined, — even  when  the  labellum  is  very 
narrow  or  quite  simple,  as  in  Malaxis,  Herminium, 
or  Habenaria. 

We  thus  see  that  an  Orchid-flower  consists  of  five 
simple  parts,  namely,  three  sepals  and  two  petals ; 
and  of  two  compounded  parts,  namely,  the  column  and 
labellum.  The  column  is  formed  of  three  pistils,  and 
generally  of  four  stamens,  all  completely  confluent. 
The  labellum  is  formed  of  one  petal  with  two  petaloid 
stamens  of  the  outer  whorl,  likewise  completely  con- 
fluent. I  may  remark,  as  making  this  fact  more 
probable,  that  in  the  allied  Marantacese  the  stamens, 
even  the  fertile  stamens,  are  often  petaloid,  and 
partially  cohere.  This  view  of  the  nature  of  the  label- 
lum explains  its  large  size,  its  frequently  tripartite 
form,  and  especially  the  manner  of  its  coherence  to  the 
column,  unlike  that  of  the  other  petals.*  As  rudi- 
mentary organs  vary  much,  we  can  thus  perhaps 
understand  the  variability,  which  as  Dr.  Hooker  informs 
me  is  characteristic  of  the  excrescences  on  the  labellum. 
In  some  Orchids  which  have  a  spur-like  nectary,  the 
two  sides  are  apparently  formed  by  the  two  modified 
stamens ;  thus  in  Gymnadenia  conopsea  (but  not  in 
Orchis  fijramidalis),  the  vessels,  proceeding  from  the 
two  antero-lateral  ovarian  groups,  run  down  the  sides 
of  the  nectary  ;  those  from  the  single  anterior  group 
run  down  the  exact  middle  of  the  nectary,  then 
returning  up  the  opposite  side  form  the  mid-rib  of  the 
labellum.  The  sides  of  the  nectary  being  thus  formed  of 
two  distinct  organs,  apparently  explains  the  tendency, 


*  Link  remarks  on  the  meaner       the  cohimn  in  his  "  Beinerkungen' 
of  coherence  of  the  labellum  to       iu  '  Bot.  Zeitung,'  1849,  p.  745. 


CJhap.  VIII. 


FLOWERS   OF   ORCHIDS. 


239 


as  in  Calanthe,  Orchis  morio,  &c.,  to  the  bifurcation  of 
its  extremity. 

The  number,  position,  and  course  of  all  the  spiral 
vessels  exhibited  in  the  diagram  (fig.  36)  were  observed 
in  some  Vandese  and  Epidendrese.*     In  the  Malaxese 


♦  It  may  he  advisable  to  give  a 
few  details  od  the  flowers  which 
I  dissected ;  but  I  looked  to  special 
points,  such  as  tlie  course  of  the 
vessels  in  the  labellum,  in  many 
cases  not  worth  here  giving.     In 
the  Vandcfe  I  traced  all  the  ves- 
sels in  Catasetiim  tridentatum  and 
saccatum;    the    great    group    of 
vessels    going  to   the    rostellum 
separate  (as  likewise  in  Mormodes) 
from  the  posterior  ovarian  group, 
beneath  the  bifurcation  supplying 
the  upper  sepal  and  fertile  anther  ; 
the  anterior  ovarian  group  runs 
a  little  way  along  the  labellum 
before   it  bifuicates  and  sends  a 
group  (a^)  up   the   front   of  the 
column;    the   vessels   proceedmg 
from  the  postero-lateral  group  run 
up   the  back  of  tl^.e   column,  on 
each  side  of  those  running  to  the 
fertih'  anther,  and  do  not  go  to 
the  edges  of  the  clinandrum.     In 
Acropera  luteola  the  base  of  the 
column,   where    the    labellum  is 
attached,  is  much  produced,  and 
the  vessels  of  the  whole  auterior 
ovarian  group  are  similarly  pro- 
duced;  those  (as)  going  up  the 
front  of  the  column  are  abruptly 
reflected  back  ;  the  vessels  at  the 
point  of  reflexion  are   curiously 
hardened,  flattened,  and  produced 
into  odd   crests  and   points.     In 
an  Oncidium  I  traced  the  vessels 
S^  to  the  viscid  gland  of  the  polli- 
nium.     Among  theEpidemlresel 
traced  all  the  vessels  in  a  Cattleya ; 
and  all  in  Evelyna  carkmta  except 
03,  which  I  did  not  search  for.  In 
the  Malaxese  I  trace  d  nlVinLiparis 
pendula  except  a,,  which  I  do  not 
believe   is   present.     In    Malaxis 
l^aladosa  I  traced  nearly  all  the 


vessels.  In  Cypripedium  harhafnm 
and  pupuratum  I  traced  all  except 
ttj,  which  I  am  nearly  sure  does 
not  exist.  In  the  Neottea;  I  traced 
in  Cephalanthera  qrandijiora   all 
the  vessels,  excepting  that  to  the 
aborted   rostellum  and   those   to 
the  two  auricles  a^  and  a.,,  which 
were  certainly  absent.     In   Epi- 
pactis  I  traced  all  excepting  ai,a2, 
and  rtj,  whifh  are  certainly  absent. 
In     Spiranthes     autumnalis     the 
vessel   Sr  runs  to  the  bottom  of 
the  fork  of  the  rostellum :   there 
are  no  vessels  to  the  membranes 
of  the  clinandrum  in  this  Orchid 
nor  in  Goody  era.    In  none  of  tlie 
Ophreoe  do  the  vessels  aj,  a^,  and 
ttg  occur.     In  Orchis  ptjramidalis 
I  traced  all  the  others,  including 
two  to  the  two  separate  stigmas : 
in  this  species  the  contrast  between 
the  vessels  of  the  labellum  and 
of  the  other  sepals  and  petals  is 
striking,  as  in  the  latter  the  ves- 
sels  do   not   branch,   whilst    the 
labellum   has   three   vessels  the 
lateral  ones  running  of  course  into 
the  antero-lateral  ovarian  group. 
In  Gymnadenia  conopsca  I  traced 
all  the  vessels ;  but  1  am  not  sure 
wliether  the  vessels  supplying  the 
sides  of  the  upper  sepal  do  not,  as 
in   the  allied  Habenaria,  wander 
from  their  proper  course  and  enter 
the  postero-lateral  ovarian  group  : 
the  vessel  Sr,  going  to  the  rostel- 
lum. enters  the  little  folded  crest 
of  membrane,  which  projects  be- 
tween the  bases  of  the  anther-cells. 
Lastly,  in  Habenaria  chlorantha  I 
traced  all  the  vessels,  excepting 
as  in  the  other  Ophreae  the  three 
of  the  inner  staminal  whorl,  and  I 
looked  Cixrofully  for  a^ :  the  vessel 


240  HOMOLOGIES   OF  THE  Chap.  VIEL 

all  were  observed  excepting  a^,  which  is  the  most 
difficult  one  to  trace,  and  apparently  is  oftenest  absent. 
In  the  CypripedccTe,  again,  all  were  traced  except  ag,* 
which,  I  feel  pretty  sure,  was  here  really  absent :  in 
this  tribe  the  stamen  (Ai)  is  represented  by  a  con- 
spicuous shield-like  rudiment,  and  ai  and  a^  are 
developed  into  two  fertile  anthers.  In  the  Ophre^B 
and  NeottCcTB  all  were  traced,  with  the  important 
exception  of  the  vessels  belonging  to  the  three  stamens 
(«!,  ^2,  and  %)  of  the  inner  whorl.  In  Gejjhalanthera 
grandiflora,  I  clearly  saw  a^  proceeding  from  the 
anterior  ovarian  group,  and  running  up  the  front  of 
the  column.  This  anomalous  Orchid  has  no  rostellum, 
and  the  vessel  marked  S^  in  the  diagram  was  entirely 
absent,  though  seen  in  every  other  species. 

Although  the  two  anthers  {a^  and  a^  of  the  inner 
whorl  are  not  fully  and  normally  developed  in  any 
Orchid,  excepting  Cypripedium,  their  rudiments  are 
generally  present  and  are  often  utilised ;  for  they  often 
form  the  membranous  sides  of  the  cup-like  clinandrum 
on  the  summit  of  the  column,  which  includes  and  pro- 
tects the  pollen-masses.  These  rudiments  thus  aid 
their  fertile  brother-anther.     In  the  young  flower-bud 


supplying  the  fertile  anther  runs  tion  of  a  freo  filament  in  front  of 

up  the  connective  membrane  be-  the   labelhim,  as  in   the  ease  of 

tween   the  two  anther-cells,  but  Glossodia  before  mentioned ;  and 

does  not  bifurcate :  the  ves-el  to  tliis  will  perhaps  account  for  thu 

the  rostellum  runs  up  to  the  top  absence  of  spiral  vessels,  proceed- 

of  the  shoulder  or  ledge  beneath  ing    from    the    anterior    ovarian 

tlie  connective  membrane  of  tlie  group    and   coalescing   with   the 

anther,  but  does  not  bifurcate  and  column.     In  Uropedium,  a  genus 

extend  to  the  two  widely-separated  which    A.    Brongniart   (' Annal. 

viscid  discs.  des.  Sc.  Nat.,'  3rd  series,  Bot.  torn. 

*    From    Irmisch's    ('Beitrdge  xiii.  p.  114)  considers  closely  allied 

zur  Biologic  der  Orchidecn,'  1853,  to,  and  even  perhaps  a  monstro- 

pp.  78  and  42)  description  of  the  sity  of,  Cypripedium,  a  third  fer- 

development  of  the  flower-bud  of  tile    anther    occupies    this   same 

Cypripedium,  it  would  appear  that  position, 
there  is  a  tendency  to  the  forma- 


CuAi.  VIII  FLOWERS   OF   ORCHIDS.  241 

of  Malaxis  paludosa,  the  close  resemblance  between  the 
two  membranes  of  the  clinandrum  and  the  fertile 
anther,  in  shape,  texture,  and  in  the  height  to  which 
the  spiral  vessels  extended,  was  most  striking  :  it  was 
impossible  to  doubt  that  in  these  two  membranes  we 
had  two  rudimentary  anthers.  In  Evelyna,  one  of  the 
Epidendrese,  the  clinandrum  was  similarly  formed,  as 
were  the  horns  of  the  clinandrum  in  Masdevallia,  which 
serve  in  addition  to  keep  the  labellum  at  the  proper 
distance  from  the  column.  In  Liparis  petidula  and 
some  other  species,  these  two  rudimentary  anthers  form 
not  only  the  clinandrum,  but  likewise  wings,  which 
project  on  each  side  of  the  entrance  into  the  stigmatic 
cavity,  and  serve  as  guides  for  the  insertion  of  the 
pollen-masses.  In  Acropera  and  Stanhopea,  as  far  as 
I  could  make  out,  the  membranous  borders  of  the 
column,  down  to  its  base,  were  also  thus  formed ;  but 
in  other  cases,  as  in  Cattleya,  the  wing-like  borders  of 
the  column  seem  to  be  simple  developments  of  the  two 
pistils.  In  this  latter  genus,  as  well  as  in  Catasetum, 
these  same  two  rudimentary  stamens,  judging  from  the 
position  of  the  vessels,  serve  chiefly  to  strengthen 
the  back  of  the  column ;  and  the  strengthening  of  the 
front  of  the  column  is  the  sole  function  of  the  third 
stamen  of  the  inner  whorl  (ag),  in  those  cases  in 
which  it  was  observed.  This  third  stamen  runs  up 
the  middle  of  the  column  to  the  lower  edge,  or  lip, 
of  the  stigmatic  cavity. 

I  have  said  that  in  the  OphreaB  and  JSTeottese  the 
spiral  vessels  of  the  inner  whorl,  marked  a^,  a^,  a^  in 
the  diagram,  are  entirely  absent,  and  I  looked  care- 
fully for  them  ;  but  in  nearly  all  the  members  of  these 
two  tribes,  two  small  papillae,  or  auricles  as  they  have 
been  often  called,  stand  in  exactly  the  position  which 
the  two  first  of  these  three  anthers  would  have  occupied, 


242  HOMOLOGIES  OF   THE  Chap.  VIII. 

had  they  been  developed.  Not  only  do  they  stand  in 
this  position,  but  the  column  in  some  cases,  as  in 
Ceplialanthera,  has  on  each  side  a  prominent  ridge, 
running  from  them  to  the  bases  or  mid-ribs  of  the  two 
upper  petals ;  that  is,  in  the  proper  position  of  the 
filaments  of  these  two  stamens.  It  is,  again,  impossible 
to  doubt  that  the  two  membranes  of  the  clinandrum 
in  Malaxis  are  formed  by  these  two  anthers  in  a 
rudimentary  and  modified  condition.  Now,  from  the 
perfect  clinandrum  of  Malaxis,  through  that  of  Spi- 
ranthes,  Goodyera,  EpipacHs  latifolia,  and  E.  palustris 
(see  fig.  16,  p.  101,  and  fig.  15,  p.  94),  to  the  minute 
and  slightly  flattened  auricles  in  the  genus  Orchis,  a 
perfect  gradation  can  be  traced.  Hence  I  conclude  that 
these  auricles  are  doubly  rudimentary ;  that  is  they 
are  rudiments  of  the  membranous  sides  of  the  clinan- 
drum, these  membranes  themselves  being  rudiments  of 
the  two  anthers  so  often  referred  to.  The  absence  of 
spiral  vessels  running  to  the  auricles  is  by  no  means 
sufficient  to  overthrow  the  views  here  advocated  as  to 
the  much  disputed  nature  of  these  structures;  that 
such  vessels  may  quite  disappear,  we  have  proof  in 
Ceplialanthera  grandiJio7'a,  in  which  the  rostellum  and 
its  vessels  are  completely  aborted. 

Finally,  then,  with  respect  to  the  six  stamens  which 
ought  to  be  represented  in  every  Orchid:  the  three 
belonging  to  the  outer  whorl  are  always  present,  the 
upper  one  being  fertile  (except  in  Cypripedium),  and 
the  two  lower  ones  invariably  petaloid  and  forming 
part  of  the  labellum.  The  three  stamens  of  the  inner 
whorl  are  less  plainly  developed,  especially  the  lower 
one,  a^,  which,  when  it  can  be  detected,  serves  only  to 
strengthen  the  column,  and,  in  some  rare  cases,  accord- 
ing to  Brown,  forms  a  separate  projection  or  filament ; 
the  two  upper  anthers  of  this  inner  whorl  are  fertile 


Chap.  VIII.  FLOWERS  OF   ORCHIDS.  243 

ill  Cypripedium,  and  in  other  cases  are  generally 
represented  either  by  membranous  expansions,  or  by 
minute  auricles  without  spiral  vessels.  These  auricles, 
however,  are  sometimes  quite  absent,  as  in  some  species 
of  Ophrys. 

On  this  view  of  the  homologies  of  Orchid-flowers, 
we  can  understand  the  existence  of  the  conspicuous 
central  column, — the  large  size,  generally  tripartite 
form,  and  peculiar  manner  of  attachment  of  the  la- 
bellum, — the  origin  of  the  clinandrum, — the  relative 
position  of  the  single  fertile  anther  in  most  of  the 
genera,  and  of  the  two  fertile  anthers  in  Cypripedium, 
— the  position  of  the  rostellum,  as  well  as  of  all  the 
other  organs, — and  lastly,  the  frequent  occurrence  of  a 
bilobed  stigma,  and  the  occasional  occurrence  of  two 
distinct  stigmas.  I  have  encountered  only  one  case  oi 
dijQficulty,  namely  in  Habenaria  and  the  allied  genus, 
Bonatea.  These  flowers  have  undergone  such  an 
extraordinary  amount  of  distortion,  owing  to  the  wide 
separation  of  their  anther-cells  and  of  the  two  viscid 
discs  of  the  rostellum,  that  any  anomaly  in  them  is 
the  less  surprising.  The  anomaly  relates  only  to  the 
vessels  supplying  the  sides  of  the  upper  sepal  and 
of  the  two  upper  petals ;  for  the  vessels  running  into 
their  midribs  and  into  all  the  other  more  important 
organs  pursue  the  same  identical  course  as  in  the  other 
Ophrese.  The  vessels  which  supply  the  sides  of  the 
upper  sepal,  instead  of  uniting  with  the  midrib  and 
entering  the  posterior  ovarian  group,  diverge  and  enter 
the  postero-lateral  groups.  Again,  the  vessels  on  the 
anterior  side  of  the  two  upper  petals,  instead  of  uniting 
with  those  of  the  midrib  and  entering  the  postero- 
lateral ovarian  groups,  diverge,  or  wander  from  their 
proper  course,  and  enter  the  antero-lateral  groups. 

This  auomaly  is  so  far  of  iuiportance,  as  it  throws 


244  HOMOLOGIES   OF   THE  Chap.  VIII. 

some  doubt  on  the  view  tliat  tlie  labellum  is  always 
an  organ  compounded  of  one  petal  and  two  petaloid 
stamens ;  for  if  any  one  were  to  assume  that  from  some 
unknown  cause  the  lateral  vessels  of  the  lower  petals 
had  diverged  in  an  early  progenitor  of  the  Orchidean 
order  from  their  proper  course  into  the  antero-lateral 
ovarian  groups,  and  that  this  structure  had  been  in- 
herited by  all  existing  Orchids,  even  by  those  with  the 
smallest  and  simplest  labellums,  I  could  answer  only 
as  follows ;  but  the  answer  is,  I  think,  satisfactory. 
From  the  analogy  of  other  monocotyledonous  plants, 
we  might  expect  the  hidden  presence  of  fifteen  organs 
in  the  flowers  of  the  Orchidea?,  arranged  alternately 
in  five  whorls;  and  in  these  flowers  we  find  fifteen 
groups  of  vessels  exactly  thus  arranged.  Hence  thei  e 
is  a  strong  probability  that  the  vessels,  A2  and  A3, 
which  enter  the  sides  of  the  labellum,  not  in  one  or 
two  cases,  but  in  all  the  Orchids  seen  by  me,  and  which 
occupy  the  precise  position  which  they  would  have 
occupied  had  they  supplied  two  normal  stamens,  do 
really  represent  modified  and  petaloid  stamens,  and 
are  not  lateral  vessels  of  the  labellum  which  have 
wandered  from  their  proper  course.  In  Habenaria  and 
Bonatea,*  on   the  other  hand,  the  vessels  proceeding 


*  In  Bonatea  speciosa,  of  which  ments  of  the  two  upper   petals 

I  have  exauiined  only  dry  speci-  coh<re  with  the  labellum,  causing 

mens  sent  me  by  Dr.  Hooker,  the  it  to  have  five  segments,  which  is 

vessels  from  the  sides  of  the  upper  a  most  imusual   feet.     Tiie   two 

sepal    enter    the     postero-lateial  wonderfully  protuberant   stigmas 

ovarian     group,    exactly    as     in  also  cohere  to  the  upper  surface  of 

Habenaria.    The  two  upper  petals  the  labellum  ;  and  the  lower  sepals 

are  divided  down  to  their  bases,  apparently  also  cohere  to  its  under 

and    the    vessels    supplying  the  side.     Consequently  a   section  of 

anterior  segment  and  those  supply-  the  base  of  the  labellum  divides 

ing  the   anterior  portion   of  the  one    lower     petal,    two    petaloid 

posterior  segment  unite  and  then  anthers,  porticns  of  the  two  upper 

run,   as   in   Habenaria,   into   the  petals,  and  apparently  of  the  two 

antero-latiral     (and      therefore  lower  sepals  and  the  two  stigmas : 

wrong)  group.    The  anterior  seg-  altogether     the     section    passes 


Chap.  VIII.  FLOWEKS  OF   OECHIDS.  245 

from  the  sides  of  the  upper  sepal  and  of  the  two  upper 
petals,  which  enter  the  wrong  ovarian  groups,  cannot 
possibly  represent  any  lost  but  once  distinct  organs. 

We  have  now  finished  with  the  general  homologies 
of  the  flowers  of  Orchids.  It  is  interesting  to  look  at 
one  of  the  magnificent  exotic  species,  or,  indeed,  at 
one  of  our  humblest  forms,  and  observe  how  profoundly 
it  has  been  modified,  as  compared  with  all  ordinary 
flowers, — with  its  great  labellum,  formed  of  one  petal 
and  two  petaloid  stamens, — with  its  singular  pollen- 
masses,  hereafter  to  be  referred  to, — with  its  column 
formed  of  seven  cohering  organs,  of  which  three  alone 
perform  their  proper  function,  namely,  one  anther  and 
two  generally  confluent  stigmas, — with  the  third  stigma 
modified  into  the  rostellum  and  incapable  of  being 
fertilised, — and  with  three  of  the  anthers  no  longer 
functionally  active,  but  serving  either  to  protect  the 
pollen  of  the  fertile  anther,  or  to  strengthen  the  column, 
or  existing  as  mere  rudiments,  or  entirely  suppressed. 
What  an  amount  of  modification,  cohesion,  abortion, 
and  change  of  function  do  we  here  see  !  Yet  hidden 
in  that  column,  with  its  surrounding  petals  and  sepals, 
we  know  that  there  are  fifteen  groups  of  vessels, 
arranged  three  within  three,  in  alternate  order,  which 
probably  have  been  preserved  to  the  present  time  from 
being  developed  at  a  very  early  period  of  growth, 
before  the  shape  or  existence  of  any  part  of  the  flower 
is  of  importance  for  the  well-being  of  the  plant. 

Can  we  feel  satisfied  by  saying  that  each  Orchid  was 
created,  exactly  as  we  now  see  it,  on  a  certain  "  ideal 
type ;  "  that  the  omnipotent  Creator,  having  fixed  on 
one  plan  for  the  whole  Order,  did  not  depart  from  this 

throngli  the  whole  of  or  through       is  licreas  comiilex  anoriran  as  the 
portions  of  cither  seven  or  nine       column  of  other  Orchids, 
organs.    The  l)ase  of  tlie  labellum 


246  HOMOLOGIES.  Chap.  VIIL 

plan ;  that  he,  therefore,  made  the  same  organ  to  per- 
form diverse  functions — often  of  trifling  importance 
compared  with  their  proper  function — converted  other 
organs  into  mere  purposeless  rudiments,  and  arranged 
all  as  if  they  had  to  stand  separate,  and  then  made 
them  cohere  ?  Is  it  not  a  more  simple  and  intelligible 
view  that  all  the  Orchidese  owe  what  they  have  in 
common,  to  descent  from  some  monocotyledonous 
plant,  which,  like  so  many  other  plants  of  the  same 
class,  possessed  fifteen  organs,  arranged  alternately 
three  within  three  in  five  whorls  ;  and  that  the  now 
wonderfully  changed  structure  of  the  flower  is  due  to 
a  long  course  of  slow  modification, — each  modification 
having  been  preserved  which  was  useful  to  the  plant, 
during  the  incessant  changes  to  which  the  organic 
and  inorganic  world  has  been  exposed  ? 


CHAr.  IX.       GRADATION  OF  OEGANS.  247 


CHAPTER  IX. 

GRADATION  OF   ORGANS,  &C. — CONCLUDING  REMARKS. 

Gradation  of  organs,  of  the  rostelhim,  of  the  pollen-masses — Formation 
of  the  caudicle— Genealogical  affinities — Secretion  of  nectar^ 
Mechanism  of  the  movement  of  the  pollinia — Uses  of  the  petals — 
Production  of  seed — Importance  of  trifling  details  of  structure — 
Cause  of  the  great  diversity  of  structure  in  the  flowers  of  Orchids 
— Cause  of  the  perfection  of  the  contrivances — Summary  on  insect- 
agency — Nature  abhors  perpetual  self-fertilisation. 

This  chapter  will  be  devoted  to  the  consideration  of 
several  miscellaneous  subjects  which  could  not  well 
have  been  introduced  elsewhere. 

On  the  gradation  of  certain  Organs. — The  rostellum, 
the  pollinia,  the  labellum,  and,  in  a  lesser  degree, 
the  column,  are  the  most  remarkable  points  in  the 
structure  of  Orchids.  The  formation  of  the  column 
and  labellum,  by  the  confluence  and  partial  abortion  of 
several  organs,  has  been  discussed  in  the  last  chapter. 
With  respect  to  the  rostellum,  no  such  organ  exists 
in  any  other  group  of  plants.  If  the  homologies  of 
Orchids  had  not  been  pretty  well  made  out,  those 
who  believe  in  the  separate  creation  of  each  organism 
might  have  advanced  this  as  an  excellent  instance  of 
a  perfectly  new  organ  having  been  specially  created, 
and  which  could  not  have  been  developed  by  suc- 
cessive slow  modifications  of  any  pre-existing  part. 
But,  as  Robert  Brown  long  ago  remarked,  it  is  not  a 
new  organ.  It  is  impossible  to  look  at  the  two  groups 
of  spiral  vessels  (fig.  36)  running  from  the  bases  of 


248  GRADATION   OF   ORGANS.  Chap.  IX. 

the  midribs  of  the  two  lower  sepals  to  the  two  lower 
stigmas,  which  are  sometimes  quite  distinct,  and  then 
to  look  at  the  third  group  of  vessels  running  from  the 
base  of  the  mid-rib  of  the  upper  sepal  to  the  rostellum, 
which  occupies  the  exact  position  of  a  third  stigma, 
and  doubt  its  homological  nature.  There  is  every 
reason  to  believe  that  the  whole  of  this  upper  stigma, 
and  not  merely  a  part,  has  been  converted  into  the 
rostellum ;  for  there  are  plenty  of  cases  of  two  stigmas, 
but  not  one  of  three  stigmatic  surfaces  being  present 
in  those  Orchids  which  have  a  rostellum.  On  the 
other  hand,  in  Cypripedium  and  Apostasia  (the  latter 
ranked  by  Brown  in  the  Orchidean  order),  which  are 
destitute  of  a  rostellum,  the  stigmatic  surface  is  trifid. 
As  we  know  only  those  plants  which  are  now  living, 
it  is  impossible  to  follow  all  the  gradations  by  which 
the  upper  stigma  has  been  converted  into  the  rostellum  ; 
but  let  us  see  what  are  the  indications  of  such  a  change 
having  been  effected.  With  respect  to  function  the 
change  has  not  been  so  great  as  it  at  first  appears. 
The  function  of  the  rostellum  is  to  secrete  viscid  matter, 
and  it  has  lost  the  capacity  of  being  penetrated  by 
the  pollen-tubes.  The  stigmas  of  Orchids,  as  well  as 
of  most  other  plants,  secrete  viscid  matter,  the  use  of 
which  is  to  retain  the  pollen  when  brought  to  them  by 
any  means,  and  to  excite  the  growth  of  the  pollen- 
tubes.  Now  if  we  look  to  one  of  the  simplest  rostel- 
lums, — for  instance,  to  that  of  Cattleya  or  Epidendrum, 
— we  find  a  thick  layer  of  viscid  matter,  not  distinctly 
separated  from  the  viscid  surface  of  the  two  confluent 
stigmas  :  its  use  is  simply  to  affix  the  pollen-masses  to 
a  retreating  insect,  which  are  thus  dragged  out  of  the 
anther  and  transported  to  another  flower,  where  they 
are  retained  by  the  almost  equally  viscid  stigmatic 
surface.     So  that  the  oflice  of  the  rostellum  is  still  to 


Chap.  IX.  GKADATION   OF   ORGANS.  249 

secure  the  pollen-masses,  but  indirectly  by  means  of 
their  attachment  to  an  insect's  body. 

The  viscid  matter  of  the  rostellum  and  of  the 
stigma  appear  to  have  nearly  the  same  nature  ;  that 
of  the  rostellum  generally  has  the  peculiar  property  of 
quickly  drying  or  setting  hard ;  that  of  the  stigma, 
when  removed  from  the  plant,  apparently  dries  more 
quickly  than  gum-water  of  about  equal  density  or 
tenacity.  This  tendency  to  dry  is  the  more  remarkable, 
as  Gartner  *  found  that  drops  of  the  stigmatic  secre- 
tion from  Nicotiana  did  not  dry  in  two  months.  The 
viscid  matter  of  the  rostellum  in  many  Orchids  when 
exposed  to  the  air  changes  colour  with  remarkable 
quickness,  and  becomes  brownish-purple ;  and  I  have 
noticed  a  similar  but  slower  change  of  colour  in  the 
viscid  secretion  of  the  stigmas  of  some  Orchids,  as  of 
Cephalanthera  grandiflora.  When  the  viscid  disc  of  an 
Orchis,  as  Bauer  and  Brown  have  observed,  is  placed 
in  water,  minute  particles  are  expelled  with  violence 
in  a  peculiar  manner ;  and  I  have  observed  exactly 
the  same  fact  in  the  layer  of  viscid  matter  covering 
the  stigmatic  utriculi  in  an  unopened  flower  of  Mor- 
modes  ignea. 

In  order  to  compare  the  minute  structure  of  the 
rostellum  and  stigma,  I  examined  young  flower-buds 
of  Epidendrum  cochleatum  and  floribundum,  which,  when 
mature,  have  a  simple  rostellum.  The  posterior  parts 
of  both  organs  were  quite  similar.  The  whole  of 
the  rostellum  at  this  early  age  consisted  of  a  mass 
of  nearly  orbicular  cells,  containing  spheres  of  brown 
matter,  which  resolve  themselves  into  the  viscid  fluid. 
Tlie  stigma  was  covered  with  a  thinner  layer  of  similar 
cells,  and  beneath  them   were   the   coherent   spindle- 


Beitrajjo  7iir  Kenutniss  der  Befruclitung,'  1844,  p.  236. 
12 


250  GRADATION   OF   OKGANS.  Chap.  IX. 

formed  utriculi.  These  are  believed  to  be  connected 
with  the  penetration  of  the  pollen-tubes ;  and  their 
absence  in  the  rostellum  probably  accounts  for  its 
not  being  penetrated.  If  the  structure  of  the  ros- 
tellum and  of  the  stigma  is  as  here  described,  their 
only  difference  consists  in  the  layer  of  cells  which 
secrete  the  viscid  matter  being  thicker  in  the  ros- 
tellum than  in  the  stigma,  and  in  the  utriculi  having 
disappeared  from  the  former.  There  is  therefore  no 
great  difficulty  in  believing  that  the  upper  stigma, 
whilst  still  in  some  degree  fertile  or  capable  of  pene- 
tration by  the  pollen-tubes,  might  have  gradually 
acquired  the  power  of  secreting  a  larger  amount  of 
viscid  matter,  losing  at  the  same  time  its  capacity  for 
fertilisation ;  and  that  insects  smeared  with  this  viscid 
matter  removed  and  transported  the  pollen-masses  in 
a  more  and  more  effective  manner  to  the  stigmas  of 
other  flowers.  In  this  case  an  incipient  rostellum 
would  have  been  formed. 

In  the  several  tribes,  the  rostellum  presents  a 
marvellous  amount  of  diversity  of  structure ;  but  most 
of  the  differences  can  be  connected  without  very  wide 
breaks.  One  of  the  most  striking  differences  is,  that 
either  the  whole  anterior  surface  to  some  depth,  or 
only  the  internal  parts  become  viscid  ;  and  in  this 
latter  case  the  surface  retains,  as  in  Orchis,  a  mem- 
branous condition.  But  these  two  states  graduate 
into  each  other  so  closely,  that  it  is  scarcely  possible 
to  draw  any  line  of  separation  between  them :  thus, 
in  Epipactis,  the  exterior  surface  undergoes  a  vast 
change  from  its  early  cellular  condition,  for  it  becomes 
converted  into  a  highly  elastic  and  tender  membrane, 
which  is  in  itself  slightly  viscid,  and  allows  the  under- 
lying viscid  matter  readily  to  exude  ;  yet  it  acts  as  a 
membrane,  and  its  under  surfac^^  is  lined  with  much 


CuAP.  IX.  GRADATION   OF   ORGANS.  251 

more  viscid  matter.  In  Hahenaria  clilorantJia  the 
exterior  surface  is  highly  viscid,  but  still  closely  re- 
sembles, under  the  microscope,  the  exterior  membrane 
of  Epipactis.  Lastly,  in  some  species  of  Oncidium, 
&c.,  the  exterior  surface,  which  is  viscid,  differs,  as  far 
as  appearance  under  the  microscope  goes,  from  the 
underlying  viscid  layer  only  in  colour;  but  it  must 
have  some  essential  difference,  for  I  find  that,  until 
this  very  thin  exterior  layer  is  disturbed,  the  under- 
lying matter  remains  viscid ;  but,  after  it  has  been 
disturbed,  the  underlying  matter  rax3idly  sets  hard. 
The  gradation  in  the  state  of  the  surface  of  the  ros- 
tellum  is  not  surprising,  for  in  all  cases  the  surface  is 
cellular  in  the  bud ;  so  that  an  early  condition  has 
only  to  be  retained  more  or  less  perfectly. 

The  nature  of  the  viscid  matter  dift'ers  remarkably 
in  different  Orchids :  in  Listera  it  sets  hard  almost 
instantly,  more  quickly  than  plaster  of  Paris  ;  in 
]\Ialaxis  and  Angrascum  it  remains  fluid  for  several 
days  ;  but  these  two  states  pass  into  each  other  by 
many  gradations.  In  an  Oncidium  I  have  observed 
the  viscid  matter  to  dry  in  a  minute  and  a  half;  in 
some  species  of  Orchis  in  two  or  three  minutes ;  in 
Epipactis  in  ten  minutes;  in  Gymnadenia  in  two 
hours  ;  and  in  Habenaria  in  over  twenty-four  hours. 
After  the  viscid  matter  of  Listera  has  set  hard,  neither 
water  nor  weak  spirits  of  wine  has  any  effect  on  it ; 
whereas  that  of  Habenaria  hifolia,  after  having  been 
dried  for  several  months,  when  moistened  became  as 
adhesive  as  ever  it  was.  The  viscid  matter  in  some 
species  of  Orchis,  when  remoistened,  presented  an 
intermediate  condition. 

One  of  the  most  important  differences  in  the  state 
of  the  rostellum  is,  whether  or  not  the  pollinia  are 
permanently  attached  to  it.     I  do  not  alhulo  to  those 


252  GRADATION   OF   ORGANS.  Cuap.  IX. 

cases  in  which  the  upper  surface  of  the  rostellum  is 
viscid,  as  in  Malaxis  and  some  Epidendrums,  and 
simply  adheres  to  the  pollen-masses;  for  these  cases 
present  no  difficulty.  But  I  refer  to  the  so-called  con- 
genital attachment  of  the  pollinia  by  their  caudicles 
to  the  rostellum  or  viscid  disc.  It  is  not,  however, 
strictly  correct  to  speak  of  congenital  attachment,  for 
the  pollinia  are  invariably  free  at  an  early  period,  and 
become  attached  either  earlier  or  later  in  different 
Orchids.  No  actual  gradation  is  at  present  known  in 
the  process  of  attachment ;  but  it  can  be  shown  to 
depend  on  very  simple  conditions  and  changes.  In 
the  Epidendreae  the  pollinia  consist  of  a  ball  of  waxy 
pollen,  with  a  long  caudicle  (formed  of  elastic  threads 
with  adherent  pollen-grains),  which  never  becomes 
spontaneously  attached  to  the  rostellum.  In  some  of 
the  Vandese,  as  in  Gymhidium  giganteum,  on  the  other 
hand,  the  caudicles  are  congenitally  (in  the  above 
sense)  attached  to  the  pollen-masses,  but  their  struc- 
ture is  the  same  as  in  the  Epidendrese,  with  the  sole 
difference,  that  the  extremities  of  the  elastic  threads 
adhere  to,  instead  of  merely  lying  on,  the  upper  lip  of 
the  rostellum. 

In  a  form  allied  to  Cymbidium,  namely,  Oncidium 
unguic'ulatiim,  I  studied  the  development  of  the  cau- 
dicles. At  an  early  period  the  pollen-masses  are 
enclosed  in  membranous  cases,  which  soon  rupture  at 
one  point.  At  this  early  period,  a  layer  of  rather 
large  cells,  including  remarkably  opaque  matter,  may 
be  detected  within  the  cleft  of  each  pollen-mass.  Tiiis 
matter  can  be  traced  as  it  gradually  changes  into  a 
translucent  substance  which  forms  the  threads  of  the 
caudicles.  As  the  change  progresses,  the  cells  them- 
selves disappear.  Finally  the  threads  at  one  end  ad- 
here to  the  waxy  pollen-masses,  and  at  the  other  end 


Chap.  IX.  GRADATION   OF   ORGANS.  253 

after  protruding  through  a  small  opening  in  the  mem- 
branous case  in  a  semi-developed  state,  they  adhere 
to  the  rostellum,  against  which  the  anther  is  pressed. 
So  that  the  adhesion  of  the  caudicle  to  the  back  of  the 
rostellum  seems  to  depend  solely  on  the  early  rupturing 
of  the  anther-case,  and  on  a  slight  protrusion  of  the 
caudicles,  before  they  have  become  fully  developed  and 
hardened. 

In  all  the  Orchideoe  a  portion  of  the  rostellum  is 
removed  by  insects  when  the  pollinia  are  removed ;  for 
the  viscid  matter,  though  conveniently  spoken  of  as  a 
secretion,  is  in  fact  part  of  the  rostellum  in  a  modified 
condition.  But  in  those  species  which  have  their 
caudicles  attached  at  an  early  period  to  the  rostellum, 
a  membranous  or  solid  portion  of  its  exterior  surface  in 
an  unmodified  condition  is  likewise  removed.  In  the 
Vandeae  this  portion  is  sometimes  of  considerable  size 
(forming  the  disc  and  pedicel  of  the  pollinium),  and 
gives  to  their  pollinia  their  remarkable  character ;  but 
the  differences  in  the  shape  and  size  of  the  removed 
portions  of  the  rostellum  can  be  finely  graduated  to- 
gether, even  within  the  single  tribe  of  the  Yandeae ; 
and  still  more  closely  by  commencing  with  the  minute 
oval  atom  of  membrane  to  which  the  caudicle  of  Orchis 
adheres,  passing  thence  to  that  of  Hahenaria  hifolia,  to 
that  of  H.  cJilorantha  with  its  drum -like  pedicel,  and 
thence  through  many  forms  to  the  great  disc  and 
pedicel  of  Catasetum. 

In  all  the  cases  in  which  a  portion  of  the  exterior 
surface  of  the  rostellum  is  removed  together  with  the 
caudicles  of  the  pollen-masses,  definite  and  often  com- 
plicated lines  of  separation  are  formed,  so  as  to  allow 
of  the  easy  separation  of  the  removed  portions.  But 
the  formation  of  these  lines  of  separation  does  not 
differ  much  from  the  process  by  which  certain  portions 


254  GKADATION   OF   ORGANS.  Chap.  IX. 

of  the  exterior  surface  of  the  rostellum  assume  a  con- 
dition intermediate  between  that  of  unaltered  mem- 
brane and  of  viscid  matter,  which  has  been  already 
alluded  to.  The  actual  separation  of  portions  of  the 
rostellum  depends  in  many  cases  on  the  excitement 
from  a  touch ;  but  how  a  touch  thus  acts  is  at  present 
inexplicable.  Such  sensitiveness  in  the  stigma  to  a 
touch  (and  the  rostellum,  as  we  know,  is  a  modified 
stigma),  and  indeed  in  almost  every  other  part,  is  by 
no  means  a  rare  quality  in  plants. 

In  Listera  and  Neottea,  if  the  rostellum  is  touched, 
even  by  a  human  hair,  two  points  rupture  and  the 
loculi  containing  the  viscid  matter  instantly  expel  it. 
Here  we  have  a  case  towards  which  as  yet  no  gradation 
is  known.  But  Dr.  Hooker  has  shown  that  the  ros- 
tellum is  at  first  cellular,  and  that  the  viscid  matter 
is  developed  within  the  cells,  as  in  other  Orchids. 

The  last  difference  which  I  will  mention  in  the 
state  of  the  rostellum  of  various  Orchids  is  the  exist- 
ence in  many  Ophrese  of  two  widely-separated  viscid 
discs,  sometimes  included  in  two  separate  pouches. 
Here  it  appears  at  first  sight  as  if  there  were  two 
rostella ;  but  there  is  never  more  than  one  medial 
group  of  spiral  vessels.  In  the  Vanclese  we  can  see 
how  a  single  viscid  disc  and  a  single  pedicel  might 
become  divided  into  two ;  for  in  some  Stanhopeas  the 
heart-shaped  disc  shows  a  trace  of  a  tendency  to  divi- 
sion; and  in  Angrsecum  we  have  two  distinct  discs 
and  two  pedicels,  either  standing  close  together  or 
removed  only  a  little  way  apart. 

It  might  be  thought  that  a  similar  gradation  from  a 
single  rostellum  into  what  appears  like  two  distinct  ros- 
tella was  shown  still  more  plainly  in  the  Ophrese  ;  for 
we  have  the  following  series, — in  Orchis  injramidalis  a 
single  disc  enclosed  in  a  single  pouch — in  Aceras  two 


Chap.  IX.  GEADATION   OF   ORGANS.  255 

discs  touching  and  affecting  each  other's  shapes,  but 
not  actually  joined — in  Orchis  latifolia  and  maculata 
two  quite  distinct  discs  but  with  the  pouch  still 
showing  plain  traces  of  division;  and,  lastly,  in 
Ophrys  we  have  two  perfectly  distinct  pouches,  in- 
cluding of  course  two  perfectly  distinct  discs.  Bu^ 
this  series  does  not  indicate  the  former  steps  by  whic? 
a  single  rostellum  became  divided  into  two  distinct 
organs ;  on  the  contrary,  it  shows  how  the  rostel 
lum,  after  having  been  anciently  divided  into  two 
organs,  has  now  in  several  cases  been  reunited  into 
a  single  organ. 

This  conclusion  is  founded  on  the  nature  of  the  little 
medial  crest,  sometimes  called  the  rostellate  process, 
between  the  bases  of  the  two  anther-cells  (see  fig.  1, 
B  and  D,  p.  8).  In  both  divisions  of  the  Ophrese — 
namely  the  species  having  naked  discs  and  those 
having  discs  enclosed  in  a  pouch — whenever  the  two 
discs  come  into  close  juxta-position,  this  medial  crest 
or  process  appears.*  On  the  other  hand,  when  the  two 
discs  stand  widely  apart,  the  summit  of  the  rostellum 
between  them  is  smooth,  or  nearly  smooth.  In  the 
Frog  Orchis  {Peristylus  viridis)  the  overarching  sum- 
mit is  bent  like  the  roof  of  a  house ;  and  here  we  see 
the  first  stage  in  the  formation  of  the  folded  crest.  In 
Herminium  monorchis,  however,  which  has  two  separate 
and  large  discs,  a  crest,  or  solid  ridge,  is  rather  more 
plainly  developed  than  might  have  been  expected. 
In  Gijmnadenia  eonopsea,  Orchis  macidata,  and  others, 
the   crest  consists  of  a  hood  of  thin  membrane ;    in 


*  Professor Babingtou  ('Manual  from  the  other  genera  of  Ophreaj. 

of  British  Botany,'  3rd  edit.)  uses  The   group  of  spiral  vessels,  pro- 

the  existence  of  this  "rostellate  perly  helonging  to  the  rostellum, 

process  "  as  a  chiiracter  to  separate  runs  up,  aud  even  into,  the  base 

Orchis,  (iymnadcuia,  and  Aceras  of  this  crest  or  process. 


256  GEADATION  OF  ORGANS.       Chap.  IX. 

0.  mascula  the  two  sides  of  the  hood  partly  adhere ; 
and  in  0.  j^yramidalis  and  in  Aceras  it  is  converted 
into  a  solid  ridge.  These  facts  are  intelligible  only 
on  the  view,  that,  whilst  the  two  discs  were  gradually 
brought  together,  during  a  long  series  of  generations, 
the  intermediate  portion  or  summit  of  the  rostellum 
became  more  and  more  arched,  until  a  folded  crest, 
and  finally  a  solid  ridge  was  formed. 


Rostellum  of  CATASETUia. 

an.  antennas  of  rostellum.  I  ped.  pedicel  of  rostellum,  to  which 

d.     viscid  disc.  I  the  pollen-masses  are  attached. 

Whether  we  compare  together  the  state  of  the  ros- 
tellum in  the  various  tribes  of  the  Orchidese,  or  com- 
pare the  rostellum  with  the  pistil  and  stigma  of  an 
ordinary  flower,  the  differences  are  wonderfully  great. 
A  simple  pistil  consists  of  a  cylinder  surmounted  by 
a  small  viscid  surface.  Now,  see  what  a  contrast  the 
rostellum  of  Catasetum,  when  dissected  from  all  the 
other  elements  of  the  column,  presents ;  and  as  I 
traced  all  the  vessels  in  this  Orchid,  the  drawing  may 
b(^  trusted  as  approximately  accurate.    The  whole  organ 


Ohap.  JX.  gradation    OF   ORGANS.  257 

has  lost  its  normal  function  of  being  fertilised.  Its 
shape  is  most  singular,  with  the  upper  end  thickened, 
bent  over  and  produced  into  two  long  tapering  and 
sensitive  antennae,  each  of  these  being  hollow  within, 
like  an  adder's  fang.  Behind  and  between  the  bases 
of  these  antennae  we  see  the  large  viscid  disc,  attached 
to  the  pedicel ;  the  latter  differs  in  structure  from  the 
underlying  portion  of  the  rostellum,  and  is  separated 
from  it  by  a  layer  of  hyaline  tissue,  which  spontaneously 
dissolves  when  the  flower  is  mature.  The  disc,  attached 
to  the  surrounding  parts  by  a  membrane  which  ruptures 
as  soon  as  it  is  excited  by  a  touch,  consists  of  strong 
upper  tissue,  with  an  underlying  elastic  cushion, 
coated  with  viscid  matter;  and  this  again  in  most 
Orchids  is  overlaid  by  a  film  of  a  differeiifc  nature. 
What  an  amount  of  specialisation  of  paifcs  do  we 
here  behold  !  Yet  in  the  comparatively  few  Orchids 
described  in  this  volume,  so  many  and  such  plainly- 
marked  gradations  in  the  structure  of  the  rostellum 
have  been  described,  and  such  plain  facilities  for  the 
conversion  of  the  upper  pistil  into  this  organ,  that,  we 
may  well  believe,  if  we  could  see  every  Orchid  which 
has  ever  existed  throughout  the  world,  we  should  find 
all  the  gaps  in  the  existing  chain,  and  every  gap  in 
in  many  lost  chains,  filled  up  by  a  series  of  easy 
transitions. 

We  now  come  to  the  second  great  peculiarity  in  the 
Orchideae,  namely  their  pollinia.  The  anther  opens 
early,  and  often  deposits  the  naked  masses  of  pollen  on 
the  back  of  the  rostellum.  This  action  is  prefigured 
in  Canna,  a  member  of  a  family  nearly  related  to  the 
Orchideae,  in  which  the  pollen  is  deposited  on  the  pistil, 
close  beneath  the  stigma.  In  the  state  of  the  pollen 
there  is  great  diversity :  in  Cypripedium  and  Vanilla 


258  GRADATION  OF   ORGANS.  Chap.  IX 

single  grains  are  embedded  in  a  glutinous  fluid  ;  in 
all  the  other  Orchids  seen  by  me  (except  the  degraded 
Oephalanthera)  the  grains  are  united  three  or  four 
together.*  These  compound  grains  are  tied  one  to 
the  other  by  elastic  threads,  but  they  often  form 
packets  which  are  tied  together  in  like  manner,  or 
they  are  cemented  into  the  so-called  waxy  masses. 
The  waxy  masses  graduate  in  the  Epidendreae  and 
Vandese  from  eight  to  four,  to  two,  and,  by  the  co- 
hesion of  the  two,  into  a  single  mass.  In  some  of  the 
Epidendrese  we  have  both  kinds  of  pollen  within  the 
same  anther,  namely,  large  waxy  masses,  and  caudicles 
formed  of  elastic  threads  with  numerous  compound 
grains  adhering  to  them. 

I  can  throw  no  light  on  the  nature  of  the  cohesion 
of  the  pollen  in  the  waxy  masses  ;  when  they  are 
placed  in  water  for  three  or  four  days,  the  compound 
grains  readily  fall  apart ;  but  the  four  grains  of  which 
each  is  formed  still  firmly  cohere  ;  so  that  the  nature 
of  the  cohesion  in  the  two  cases  must  be  different. 
1'he  elastic  threads  by  which  the  packets  of  pollen  are 

*  In    several  cases  I  have  ob-  tubes  are,  at  least  at  first,  formed 

served   four   tubes   emitted   fiom  exclusively  at  the  expense  of  the 

the  four  giains  which  form  one  of  contents  of  the  pollen -grains, 

the  compound   grains.     In   some  Having  alluded  to  the  monstrous 

senii-m.onsttous  flowers  of  Ma/aa-/.s  flowers  of  the  Aceias,  I  will  add 

paludosa,  and  of  Aceras  anthropo-  thai  I  examined  several  (always 

phora,  and   in   perfect  flowers  of  the  lowest  on  the  spike)  in  which 

JSeottia  nidus-avis,  i  have  observed  the  labellum  was  hardly  developed, 

tubes   emitted   from    the   pollen-  and  w^as  pressed  close  agninst  the 

grains,    whils^t    still    within   the  stigma.     The   mstellum  was   not 

anther  and  not   m   contact  with  developed,  so  that  the  polliida  did 

the  fctigma.     I  have  thought  this  not  possess  viscid  discs  ;   but  the 

worth   mentioning    as  R.  Brown  most  curious  feature  was,  that  the 

('  Linn.  Transact.'  vol.  xvi.  p.  729)  two  anther-cells  had  become,  appa- 

states,  apparently  with  some  sur-  rently  in  consequence  of  the  post- 

prise,  that  the  pollen-tubes  wt  re  tion  of  the  rudimentary  labellum. 

eniitted   from  the   pollen,  whilst  widely  separated,  and  were  joined 

Htill  within  the  anther,  in  a  decay-  by  a  connective  membrane,  almost 

ing  flower  of  Asclcpias.      These  as   broad   as   that   of   Haheiiaria 

tases  show    that   the    protruding  ddoraiitha  J 


Chap.  IX.       GRADATION  OF  ORGANS.  259 

tied  together  in  the  Ophreae,  and  which  run  far  up 
inside  the  waxy  masses  of  the  Vandeae,  are  also  of  a 
different  nature  from  the  cementing  matter ;  for  the 
threads  are  acted  on  by  chloroform  and  by  long  im- 
mersion in  spirits  of  wine ;  whilst  these  fluids  have  no 
particular  action  on  the  cohesion  of  the  waxy  masses. 
In  several  EpidendresB  and  Yandeae  the  exterior  grains 
of  the  pollen-masses  difter  from  the  interior  grains,  in 
being  larger,  and  in  having  yellower  and  much  thickei 
walls.  So  that  in  the  contents  of  a  single  anther-cell 
we  see  a  surprising  degree  of  differentiation  in  the 
pollen,  namely,  grains  cohering  by  fours,  then  being 
either  tied  together  by  threads  or  cemented  together 
into  solid  masses,  with  the  exterior  grains  different 
from  the  interior  ones. 

In  the  Vandeae,  the  caudicle,  which  is  composed  of 
fine  coherent  threads,  is  developed  from  the  semi-fluid 
contents  of  a  layer  of  cells.  As  I  find  that  chloroform 
has  a  peculiar  and  energetic  action  on  the  caudicles 
of  all  Orchids,  and  likewise  on  the  glutinous  matter 
which  envelopes  the  pollen-grains  in  Cypripedium, 
and  which  can  be  drawn  out  into  threads,  we  may 
suspect  that  in  this  latter  genus, — the  least  differenti- 
ated in  structure  of  all  the  Orchideae, — we  see  the 
primordial  condition  of  the  elastic  threads  by  which 
the  pollen-grains  are  tied  together  in  other  and  more 
highly  developed  species.* 


*  Auguste    de    Saint    Hilairc  drop    by   drop   into   the  anther. 

('Lemons  de  Botaniqne,'  &c..  1841,  Had  not  so  eminent  an  authority 

p.  447)  says  that  the  elastic  threads  made  this  statement,  I  should  not 

exist  in  the  early  bud,  after  the  have  noticed  it.     It  is  ccrtiiinlv 

jjoUen-grains    hiive    been    partly  erroneous.     In  buds  of  Epipactis 

formed,  as  a  thick  creamy  fluid.  latifoUa    I    opened    the    Muther, 

He  adds  tliat  his  observations  on  whilst   perftctly  clos;  d   and   free 

Ophrys  apifera  have  shown  him  from  ihe  rostelluin,  and  found  the 

that  this  fluid  is  secreted  by  the  pollen-grains    united    by   elastic 

robtellum,    and    is   slowly    forced  threads.     Ccvhalajithcrn   <jrandi' 


260  GRADATION   OF   ORGANS.  Chap.  IX 

The  caudicle,  when  largely  developed  and  destitute 
of  pollen-grains,  is  the  most  striking  of  the  many  pecu- 
liarities presented  by  the  pollinia.  In  some  Neottese, 
especially  in  G-oodyera,  we  see  it  in  a  nascent  con- 
dition, projecting  just  beyond  the  pollen-mass,  with 
the  threads  only  partially  coherent.  In  the  Yandese 
by  tracing  the  gradation  from  the  ordinary  naked 
condition  of  the  caudicle,  through  Lycaste  in  which 
it  is  almost  naked,  through  Calanthe,  to  Gymhidium 
giganteum,  in  which  it  is  covered  with  pollen-grains,  it 
seems  probable  that  its  ordinary  condition  has  been 
arrived  at  by  the  modification  of  a  pollinium  like 
that  of  one  of  the  Epidendreae ;  namely,  by  the  abor- 
tion of  the  pollen-grains  which  primordially  adhered  to 
separate  elastic  threads,  and  afterwards  by  the  cohesion 
of  these  threads. 

In  the  Ophreae  we  have  better  evidence  than  is 
afforded  by  gradation,  that  their  long,  rigid  and 
naked  caudicles  have  been  developed,  at  least  partially, 
by  the  abortion  of  the  greater  number  of  the  lower 
pollen-grains  and  by  the  cohesion  of  the  elastic  threads 
by  which  these  grains  were  tied  together.  I  had  often 
observed  a  cloudy  appearance  in  the  middle  of  the 
translucent  caudicles  in  certain  species ;  and  on  care- 
fully opening  several  caudicles  of  Orchis  pyramidalis, 
i  found  in  their  centres,  fully  half-way  down  between 
the  packets  of  pollen  and  the  viscid  disc,  many  pollen- 
grains  (consisting,   as   usual,  of  four  united  grains). 


Aora  hns  no  rostellum  to  secrete  and  stigma ;   yet  I  found  in  one 

the    above    thick   fluid,    yet   the  of  thse  auricles  a  distinct  caudicle 

pollen-grains  are  thus  united.    In  (which  necessarily  had  no  disc  at 

a  monstrous  specimen    of   Orchis  its  extremity),  and  this  caudicle 

pyramidalis  the  auricles,  or  nidi-  could    not     possibly    have    been 

mentary  anthers  on  eacli  side  of  secreted     by    the     rostellum     oi 

the    proper   anther,   hnd   become  stigma.     I   could   advance    addi 

partly  developed,  and  they  stood  tiomil  evidence,  but  it  would  be 

quile  on  one  side  of  the  robtellum  su[)erfluoud. 


CuAP.  IX  GRADATION   OF   OEGANS.  261 

lying  quite  loose.  These  grains,  from  their  embedded 
position,  could  never  by  any  possibility  have  been  left 
on  the  stigma  of  a  flower,  and  were  absolutely  useless. 
Those  who  can  persuade  themselves  that  purposeless 
organs  have  been  specially  created,  will  think  little  of 
this  fact.  Those  on  the  contrary,  who  believe  in  the 
slow  modification  of  organic  beings,  will  feel  no 
surprise  that  the  changes  have  not  always  been  per- 
fectly effected, — that,  during  and  after  the  many 
inherited  stages  of  the  abortion  of  the  lower  pollen- 
grains  and  of  the  cohesion  of  the  elastic  threads, 
there  should  still  exist  a  tendency  to  the  production 
of  a  few  grains  where  they  were  originally  developed  ; 
and  that  these  should  consequently  be  left  entangled 
within  the  now  united  threads  of  the  caudicle.  They 
will  look  at  the  little  clouds  formed  by  the  loose 
pollen-grains  within  the  caudicles  of  Orchis  pjramidalis, 
as  good  evidence  that  an  early  progenitor  of  this  plant 
had  pollen-masses  like  those  of  Epipactis  or  Goodyera, 
and  that  the  grains  slowly  disappeared  from  the  lower 
parts,  leaving  the  elastic  threads  naked  and  ready  to 
cohere  into  a  true  caudicle. 

As  the  caudicle  plays  an  important  part  in  the 
fertilisation  of  the  flower,  it  might  have  been  deve- 
loped from  one  in  a  nascent  condition,  such  as  we  see 
in  Epipactis,  to  any  required  length  merely  by  the 
continued  preservation  of  varying  increments  in  its 
length,  each  beneficial  in  relation  to  other  changes  in 
the  structure  of  the  flower,  and  without  any  abortion 
of  the  lower  pollen-grains.  But  we  may  conclude 
from  the  facts  just  given,  that  this  has  not  been  the 
sole  means, — that  the  caudicle  owes  much  of  its  length 
to  such  abortion.  That  in  some  cases  it  has  subse- 
quently been  largely  increased  in  length  by  natural 
selection,  is  highly  probable;  for  in  Bonatea  sj^eciosa 


262  LINES  OF  DESCENT.  Chap.  IX. 

the  caudicle  is  actually  more  than  thrice  as  long  as  the 
elongated  pollen-masses  ;  and  it  is  highly  improbable 
that  so  lengthy  a  mass  of  grains,  slightly  cohering 
together  by  the  aid  of  elastic  threads,  should  ever  have 
existed,  as  an  insect  could  not  have  safely  transported 
and  applied  a  mass  of  this  shape  and  size  to  the 
stigma  of  another  flower. 

We  have  hitherto  considered  gradations  in  the  state 
of  the  same  organ.  To  any  one  with  more  knowledge 
than  I  possess,  it  would  be  an  interesting  subject  to 
trace  the  gradations  between  the  several  species  and 
groups  of  species  in  this  great  and  closely-connected 
order.  But  to  make  a  perfect  gradation,  all  the  extinct 
forms  which  have  ever  existed,  along  many  lines  of 
descent  converging  to  the  common  progenitor  of  the 
group,  would  have  to  be  called  back  into  life.  It  is 
due  to  their  absence,  and  to  the  consequent  wide  gaps 
in  the  series,  that  we  are  enabled  to  divide  the  exist- 
ing species  into  definable  groups,  such  as  genera, 
families,  and  tribes.  If  there  had  been  no  extinction, 
there  would  still  have  been  great  lines  or  branches  of 
special  development, — the  Vandese,  for  instance,  would 
still  have  been  distinguishable  as  a  great  body,  from 
the  great  body  of  the  Ophrese  ;  but  ancient  and  inter- 
mediate forms,  very  different  probably  from  their 
present  descendants,  would  have  rendered  it  utterly 
impossible  to  separate  by  distinct  characters  the  one 
great  body  from  the  other. 

I  will  venture  on  only  a  few  more  remarks.  Cypri- 
pedium,  in  having  three  stigmas  developed,  and  there- 
fore in  not  possessing  a  rostellum,  in  having  two  fertile 
anthers  with  a  large  rudiment  of  a  third,  and  in  the 
state  of  its  pollen,  seems  a  remnant  of  the  order  whilst 
in  a  simpler  or  more  generalised  condition.     Apostasia 


Chap.  IX.  LINES   OF  DESCENT.  263 

is  a  related  genus,  placed  by  Brown  amongst  the 
Orchideae,  but  by  Lindley  in  a  small  distinct  family. 
These  broken  groups  do  not  indicate  to  us  the  structure 
of  the  common  parent-form  of  all  the  Orchidese,  but 
they  serve  to  show  the  probable  state  of  the  order  in 
ancient  times,  when  none  of  the  forms  had  become  so 
widely  differentiated  from  one  another  and  from  other 
plants,  as  are  the  existing  Orchids,  especially  the 
Yandese  and  Ophrcfe  ;  and  when,  consequently,  the 
order  made  a  nearer  approach  in  all  its  characters, 
than  it  does  at  present,  to  such  allied  groups  as  the 
Marantaceae. 

With  respect  to  other  Orchids,  we  can  see  that  an 
ancient  form,  like  one  of  the  sub-tribe  of  the  Pleuro- 
thallidae,  some  of  which  have  waxy  pollen-masses  with 
a  minute  caudicle,  might  have  given  rise,  by  the  entire 
abortion  of  the  caudicle,  to  the  Dendrobise,  and  by  an 
increase  of  the  caudicle  to  the  Epidendrefe.  Cymbi- 
dium  shows  us  how  simply  a  form  like  one  of  our 
present  Epidendrese  could  be  modified  into  one  of  the 
Vandese.  The  Neottese  stand  in  nearly  a  similar  relation 
to  the  higher  Ophreae,  which  the  Epidendrefe  do  to  the 
higher  Vandese.  In  certain  genera  of  the  Neotteae  we 
have  eompound  pollen-grains  cemented  into  packets 
and  tied  together  by  elastic  threads,  which  project  and 
thus  form  a  nascent  caudicle.  But  this  caudicle  does 
not  protude  from  the  lower  end  of  the  pollinium  as  in 
the  OphresB,  nor  does  it  always  protrude  from  the  ex- 
treme upper  end  in  the  Neottese,  but  sometimes  at  an 
intermediate  level ;  so  that  a  transition  in  this  respect 
is  far  from  impossible.  In  Spiranthes,  the  back  of  the 
rostellum,  lined  with  viscid  matter,  is  alone  removed  : 
the  front  part  is  membranous,  and  ruptures  like  the 
pouch-formed  rostellum  of  the  Ophreae.  An  ancient 
form  combining  most  of  the  characters,  but  in  a  less 


264  LINES  OF   DESCENT.  Chap.  IX. 

developed  state,  of  Goodyera,  Epipactis,  and  Spiranthes, 
all  members  of  the  Neottese,  could  by  further  slight 
modifications  have  given  birth  to  the  tribe  of  the 
Ophreae. 

Hardly  any  question  in  Natural  History  is  more 
vague  and  diflicult  to  answer  than  what  forms  ought 
to  be  considered  as  the  highest  in  a  large  group ;  *  for 
all  are  well  adapted  to  their  conditions  of  life.  If  we 
look  to  successive  modifications,  with  difi'erentiation  of 
parts  and  consequent  complexity  of  structure,  as  the 
standard  of  comparison,  the  Ophreae  and  Yandese  will 
stand  the  highest  among  the  Orchidea3.  Are  we  to  lay 
much  stress  on  the  size  and  beauty  of  the  flower,  and 
on  the  size  of  the  whole  plant  ?  if  so,  the  Yandeae  are 
pre-eminent.  They  have,  also,  rather  more  complex 
poUinia,  with  the  pollen-masses  often  reduced  to  two. 
The  rostellum,  on  the  other  hand,  has  apparently  been 
more  modified  from  its  primordial  stigmatic  nature  in 
the  Ophreae,  than  in  the  Yandeae.  In  the  Ophreae  the 
stamens  of  the  inner  whorl  are  almost  entirely  sup- 
pressed,— the  auricles — mere  rudiments  of  rudiments — 
being  alone  retained;  and  even  these  are  sometimes 
lost.  These  stamens,  therefore,  have  suffered  extreme 
reduction;  but  can  this  be  considered  as  a  sign  of 
highness?  I  should  doubt  whether  any  member  of 
the  Orchidean  order  has  been  more  profoundly  modified 
in  its  whole  structure  than  Bonatea  specicsay  one  of  the 
Ophreae.  So  again,  within  this  same  tribe,  nothing 
can  be  more  perfect  than  the  contrivances  in  Orchis 
pyramidalis  for  its  fertilisation.  Yet  an  ill -defined 
feeling  tells  me  to  rank  the  magnificent  Yandeae  as 
the  highest.     When  we  look  within  this  tribe  at  the 


*  The  fullest  and  the  most  able       his   *  Eiitwickelungs-Gesotze   der 
discussion  un  this  ditiiculr,  subject       Organischen  Welt/  1S58. 
'a  by    Pioiesbor  11.  G.  Bionn  in 


Chap.  IX        SECEETION  OF  NECTAR.  265 

elaborate  mechanism  for  the  ejection  and  transportal 
of  the  pollinia  of  Catasetum,  with  the  sensitive  ros- 
tellum  so  wonderfully  modified,  with  the  sexes  borne 
on  distinct  plants,  we  may  perhaps  give  the  palm  of 
victory  to  this  genus. 

SECRETION   OF   NECTAR. 

Many  Orchids,  both  our  native  species  and  the 
exotic  kinds  cultivated  in  our  hothouses,  secrete  a 
copious  supply  of  nectar.  I  have  found  the  horn-like 
nectaries  of  Aerides  filled  with  fluid  ;  and  Mr.  Kodgers, 
of  Sevenoaks,  informs  me  that  he  has  taken  crystals 
of  sugar  of  considerable  size  from  the  nectary  of  A, 
cornutum.  The  nectar-secreting  organs  of  the  Orchideae 
present  great  diversities  of  structure  and  position  in 
the  various  genera ;  but  are  almost  always  situated 
towards  the  base  of  the  labellum.  In  Disa,  however, 
the  posterior  sepal  alone,  and  in  Disperis  the  two 
lateral  sepals  together  with  the  labellum,  secrete 
nectar.  In  Bendrobium  chrysanthum  the  nectary 
consists  of  a  shallow  saucer ;  in  Evelyna,  of  two  large 
united  cellular  balls ;  and  in  Bolhophyllum  cui^reum,  of 
a  medial  furrow.  In  Cattleya  the  nectary  penetrates 
the  ovarium.  In  Angrsecum  sesquipedale  it  attains  the 
astonishing  length  of  above  eleven  inches ;  but  I  need 
not  enter  on  further  details.  The  fact,  however, 
should  be  recalled,  that  in  Coryanthes  the  nectar- 
secreting  glands  pour  forth  an  abundance  of  almost 
pure  water,  which  drips  into  a  bucket  formed  by  the 
distal  part  of  the  labellum ;  and  this  secretion  serves 
to  prevent  the  bees  which  come  to  gnaw  the  surface  of 
the  labellum  from  flying  away,  and  thus  compels  them 
to  crawl  out  through  the  proper  passage. 

Although  the  secretion  of  nectar  is  of  the  highest 


266  SECRETION  OF  NECTAE.        Chap.  IX. 

importance  to  Orcliids  by  attracting  insects,  which  are 
indispensable  for  the  fertilisation  of  most  of  the  species, 
yet  good  reasons  can  be  assigned  for  the  belief*  that 
nectar  was  aboriginally  an  excretion  for  the  sake  of 
getting  rid  of  superfluous  matter  during  the  chemical 
changes  which  go  on  in  the  tissues  of  plants,  especially 
W'hilst  the  sun  shines.  The  bractese  of  some  Orchids 
have  been  observed  f  to  secrete  nectar,  and  this  cannot 
be  of  any  use  to  them  for  their  fertilisation.  Fritz 
Muller  informs  me  that  he  has  seen  such  secretion 
from  the  bracteae  of  an  Oncidium  in  its  native  Bra- 
zilian home,  as  well  as  from  the  bractese  and  from  the 
outside  of  the  upper  sepal  of  a  Notylia.  Mr.  Eodgers 
has  observed  a  similar  and  copious  secretion  from  the 
base  of  the  flower-peduncles  of  Vanilla.  The  column 
of  Acropera  and  Grongora  likewise  secretes  nectar,  as 
previously  stated,  but  only  after  the  flowers  have  been 
impregnated,  and  when  such  secretion  could  be  of  no 
use  by  attracting  insects.  It  is  in  perfect  accordance 
with  the  scheme  of  nature,  as  worked  out  by  natural 
selection,  that  matter  excreted  to  free  the  system  from 
superfluous  or  injurious  substances  should  be  utilised 
for  highly  useful  purposes.  To  give  an  example  in 
strong  contrast  with  our  present  subject,  the  larvae  of 
certain  beetles  (Cassidae,  &c.)  use  their  own  excrement 
to  make  an  umbrella-like  protection  for  their  tender 
bodies. 

It  may  be  remembered  that  evidence  was  given  in 
the  first  chapter  proving  that  nectar  is  never  found 
within  the  spur-like  nectaries  of  several  species  of 
Orchis,  but   that  various   kinds   of  insects  penetrate 


*  This   subject  has  been  fully  1876,  p.  402. 

dispussed   in  my   work  'On   the  t  Kurr,  'Ueber  die  Bedeutung 

Effects  of  Cross  and  Silffertilisa-  der  Nektarien,'  18i?8,  ]).  28. 
tion  in  the  Vegetal  ile  K  ugdom,' 


Chap.  IX.        SECKETION  OF  NECTAK,  267 

the  tender  inner  coat  with  their  proboscides,  and  suck 
the  fluid  contained  in  the  inter-cellular  spaces.  This 
conclusion  has  been  confirmed  by  Hermann  Miiller, 
and  I  have  further  shown  that  even  Lepidoptera  are 
able  to  penetrate  other  and  tougher  tissues.  It  is  an 
interesting  case  of  co-adaptation  that  in  all  the  British 
species,  in  which  the  nectary  does  not  contain  free 
nectar,  the  viscid  matter  of  the  disc  of  the  poUinium 
requires  a  minute  or  two  in  order  to  set  hard  ;  and 
it  would  be  an  advantage  to  the  plant  if  insects  were 
delayed  thus  long  in  obtaining  the  nectar  by  having 
to  puncture  the  nectary  at  several  points.  On  the 
other  hand,  in  all  the  Ophreae  which  have  nectar  ready 
stored  within  the  nectary,  the  discs  are  sufficiently 
viscid  for  the  attachment  of  the  pollinia  to  insects, 
without  the  matter  quickly  setting  liard ;  and  there 
would  therefore  be  no  advantage  to  these  plants  in 
insects  being  delayed  for  a  few  minutes  whilst  sucking 
the  flowers. 

In  the  case  of  cultivated  exotic  Orchids  which  have 
a  nectary,  without  any  free  nectar,  it  is  of  course 
impossible  to  feel  absolutely  sure  that  it  would  not 
contain  any  under  more  natural  conditions.  Nor  have 
I  made  many  comparative  observations  on  the  rate  of 
the  setting  hard  of  the  viscid  matter  of  the  disc  in 
exotic  forms.  Nevertheless  it  seems  that  some  Yandeas 
are  in  the  same  predicament  as  our  British  species  of 
Orchis  ;  thus  Calanthe  masuca  has  a  very  long  nectary, 
which  in  all  the  specimens  examined  by  me  was  quite 
dry  internally,  and  was  inhabited  by  powdery  Cocci ; 
but  in  the  intercellular  spaces  between  the  two  coats 
there  was  much  fluid ;  and  in  this  species  the  viscid 
matter  of  the  disc,  after  its  surface  had  been  disturbed, 
entirely  lost  its  adhesiveness  in  two  minutes.  In  an 
Oncidium  the  disc,  similarly  disturbed,  became  dry  in 


268  SECEETION   OF   NECTAR.  Chap.  IX. 

one  minute  and  a  half ;  in  an  Odontoglossum  in  two 
minutes ;  and  in  neither  of  these  Orchids  was  there 
any  free  nectar.  On  the  other  hand,  in  Angrsecum 
sesquiijedale,  which  has  free  nectar  stored  within  the 
lower  end  of  the  nectary,  the  disc  of  the  pollinium, 
when  removed  from  the  plant  and  with  its  surface 
disturbed,  was  strongly  adhesive  after  forty-eight 
hours. 

Sarcantlius  teritifolius  offers  a  more  curious  case. 
The  disc  quite  lost  its  viscidity  and  set  hard  in  less 
than  three  minutes.  Hence  it  might  have  been  ex- 
pected that  no  fluid  would  have  been  found  in  the 
nectary,  but  only  in  the  intercellular  spaces ;  never- 
theless there  was  fluid  in  both  places,  so  that  here  we 
have  both  conditions  combined  in  the  same  flower.  It 
is  probable  that  insects  would  sometimes  rapidly  suck 
the  free  nectar  and  neglect  that  between  the  two 
coats;  but  even  in  this  case  I  strongly  suspect  that 
they  would  be  delayed  by  a  totally  different  means 
in  sucking  the  free  nectar,  so  as  to  allow  the  viscid 
matter  to  set  hard.  In  this  plant,  the  labellum  with 
its  nectary  is  an  extraordinary  organ.  I  wished  to 
have  had  a  drawing  made  of  its  structure ;  but  found 
that  it  was  as  hopeless  as  to  give  a  drawing  of  the 
wards  of  a  complicated  lock.  Even  the  skilful  Bauer, 
with  numerous  figures  and  sections  on  a  large  scale, 
hardly  makes  the  structure  intelligible.  So  com- 
plicated is  the  passage,  that  I  failed  in  repeated 
attempts  to  pass  a  bristle  from  the  outside  of  the 
flower  into  the  nectary;  or  in  a  reversed  direction 
from  the  cut-off  end  of  the  nectary  to  the  outside.  No 
doubt  an  insect  with  a  voluntarily  flexible  proboscis 
could  pass  it  through  the  passages,  and  thus  reach 
the  nectar  ;  but  in  effecting  this,  some  delay  would 
be  caused  ;  and  time  would  be  thus  allowed  for  the 


CuAP.  IX.       SECRETION  OF  NECTAE.  269 

curious  square  viscid  disc  to  become  securely  cemented 
to  an  insect's  head  or  body. 

As  in  Epipactis  the  cup  at  the  base  of  the  labellum 
serves  as  a  nectar-receptacle,  I  expected  to  find  that 
the  analogous  cups  in  Stanhopea,  Acropera,  &c.,  would 
serve  for  the  same  purpose ;  but  I  could  never  find 
a  drop  of  nectar  in  them.  According,  also,  to  M. 
Meniere  and  Mr.  Scott  *  this  is  never  the  case  in  these 
genera,  or  in  Gongora,  Cirrhsea,  and  many  others.  In 
Catasetum  tridentatum,  and  in  the  female  form  Mona- 
chanthus,  we  see  that  the  upturned  cup  cannot 
possibly  serve  as  a  nectar-receptacle.  What  then 
attracts  insects  to  these  flowers  ?  That  they  must  bo 
attracted  is  certain  ;  more  especially  in  the  case  of  Cata- 
setum, in  which  the  sexes  stand  on  separate  plants.  In 
many  genera  of  Vandeee  there  is  no  trace  of  any  nectar- 
secreting  organ  or  receptacle  ;  but  in  all  these  cases 
(as  far  as  I  have  seen),  the  labellum  is  either  thick  and 
fleshy,  or  is  furnished  with  extraordinary  excrescences, 
as  in  the  genera  Oncidium  and  Odontoglossum.  In 
Phalasnopsis  grayidiflora  there  is  a  curious  anvil-shaped 
projection  on  the  labellum,  with  two  tendril-like  pro- 
longations from  its  extremity  which  turn  backwards 
and  apparently  serve  to  guard  the  sides  of  the  anvil,  so 
that  insects  would  be  forced  to  alight  on  its  crown. 
Even  in  our  British  Cephalanthera  grandiflora,  the 
labellum  of  which  never  contains  nectar,  there  are 
orange-coloured  ribs  and  papillae  on  the  inner  surface 
which  faces  the  column.  In  Calanthe  (fig.  26)  a  cluster 
of  odd  little  spherical  warts  projects  from  the  labellum, 
and  there  is  an  extremely  long  nectary,  which  does 
not  include  nectar ;  in  Eidophia  viridis  the  short  nec- 
tary is  equally  destitute  of  nectar,  and  the  labellum 


*  'Biillctin  Bot.  S.;c.  de  Franco,'  toin.  il.  1855,  p  352. 


270  SECRETION   OF   NECTAR.  Chap.  IX, 

is  covered  with  longitudinal,  fimbriated  ridges.  In 
several  species  of  Ophrys,  there  are  two  small  shining 
protuberances,  at  the  base  of  the  labellum,  beneath  the 
two  discs.  Innumerable  other  cases  could  be  added  of 
the  presence  of  singular  and  diversified  excrescences 
on  the  labellum ;  and  Lindley  remarks  that  their  use 
is  quite  unknown. 

From  the  position,  relatively  to  the  viscid  discs, 
which  these  excrescences  occupy,  and  from  the  absence 
of  any  free  nectar,  it  formerly  seemed  to  me  highly 
probable  that  they  afi'orded  food  and  thus  attracted 
either  Hymenoptera  or  flower-feeding  Coleoptera. 
There  is  no  more  inherent  improbability  in  a  flower 
being  habitually  fertilised  by  an  insect  coming  to 
feed  on  the  labellum,  than  in  seeds  being  habitually 
disseminated  by  birds  attracted  by  the  sweet  pulp  in 
which  they  are  embedded.  But  I  am  bound  to  state 
that  Dr.  Percy,  who  had  the  thick  and  furrowed 
labellum  of  a  Warrea  analysed  for  me  by  fermentation 
over  mercury,  found  that  it  gave  no  evidence  of  con- 
taining more  saccharine  matter  than  the  other  petals. 
On  the  other  hand,  the  thick  labellum  of  Catasetum 
and  the  bases  of  the  upper  petals  of  Mor modes  ignea, 
have  a  slightly  sweet,  rather  pleasant,  and  nutritious 
taste.  Nevertheless,  it  was  a  bold  speculation  that 
insects  were  attracted  to  the  flowers  of  various  Orchids 
in  order  to  gnaw  the  excrescences  or  other  parts  of 
their  labella;  and  few  things  have  given  me  more 
satisfaction  than  the  full  confirmation  of  this  view  by 
Dr.  Criiger,  who*  has  repeatedly  witnessed  in  the  AVest 
Indies  humble-bees  of  the  genus  Euglossa  gnawing  the 
labellum  of  Catasetum,  Coryanthes,  Gongora,  and 
Stanhopea.     Fritz   Miiller   also   has   often    found,   in 


'  Journ.-  Linn.  Soc.  Bot.'  18G4,  vol.  viii.  p.  129. 


CiiAi'.  IX.  MOVEMENTS   OF   THE    POLLINIA.  271 

South  Brazil,  the  prominences  on  the  labellum  of 
Oncidium  gnawed.  We  are  thus  enabled  to  under- 
stand the  meaning  of  the  various  extraordinary  crests 
and  projections  on  the  labellum  of  many  Orchids  ;  for 
they  invariably  stand  in  such  a  position  that  insects, 
whilst  gnawing  them,  would  be  almost  sure  to  touch 
the  viscid  discs  of  the  pollinia  and  thus  remove  them, 
afterwards  effecting  the  fertilisation  of  another  flower. 


MOVEMENTS   OF   THE    POLLINIA. 

The  pollinia  of  many  Orchids  undergo  a  movement 
of  depression,  after  they  have  been  removed  from  their 
places  of  attachment  and  have  been  exposed  for  a  few 
seconds  to  the  air.  This  is  due  to  the  contraction  of  a 
portion,  sometimes  to  an  exceedingly  minute  portion, 
of  the  exterior  surface  of  the  rostellum,  which  retains 
a  membranous  condition.  This  membrane,  as  we  have 
seen,  is  likewise  sensitive  to  a  touch,  so  as  to  rupture 
in  certain  definite  lines.  .  In  a  Maxillaria  the  middle 
part  of  the  pedicel,  and  in  Habenaria  the  whole  drum- 
like pedicel  contracts.  The  point  of  contraction  in  all 
the  other  cases  seen  by  me,  is  either  close  to  the 
surface  of  attachment  of  the  caudicle  to  the  disc,  or  at 
the  point  where  the  pedicel  is  united  to  the  disc ;  but 
both  the  disc  and  pedicel  are  parts  of  the  exterior 
surface  of  the  rostellum.  In  these  remarks  I  do  not 
refer  to  the  movements  which  are  simply  due  to  the 
elasticity  of  the  pedicel,  as  in  the  Yandese. 

The  long  strap-formed  disc  of  Gymnadenia  conopsea 
is  well  adapted  to  show  the  mechanism  of  the  move- 
ment of  depression.  The  whole  pollinium,  both  in  its 
upright  and  depressed  (but  not  closely  depressed) 
position,  has  been  shown  (p.  6ij)  in  fig.  10.  The  disc, 
in  its  uncontracted  condition  with  the  caudicle  removed, 


272  MOVEMENTS   OF   THE   POLLINIA.         Chap.  IX. 

is  seen  from  above  highly  magnified  in  the  upper  of 
the  two  adjoining  figures  ;  and  in  the  lower  figure  we 
have  a  longitudinal  section  of  the  uncontracted  disc, 
together  with  the  base  of  the  attached  and  upright 
caudicle.  At  the  broad  end  of  the  disc  there  is  a  deep 
crescent-shaped  depression,  bordered  by  a  slight  ridge 
formed  of  longitudinally  elon- 
^'"     *  gated  cells.     The  end  of  the 

caudicle  is  attached  to  the 
steep  sides  of  this  depression 
and  ridge.  When  the  disc  is 
exposed  to  the  air  for  about 
thirty  seconds,  the  ridge  con- 
tracts and  sinks  flat  down ;  in 

Disc  o^Gyrr^nadeniaconopsea.     ^^^-^^^^^    ^^    j.^gg    ^i^h   it   the 

caudicle,  which  then  lies  parallel  to  the  elongated 
tapering  part  of  the  disc.  If  placed  in  water  the 
ridge  rises,  re-elevating  the  caudicle,  and  when  re- 
exposed  to  the  air  it  sinks  again,  but  each  time  with 
somewhat  enfeebled  power.  During  each  sinking  and 
rising  of  the  caudicle,  the  whole  pollinium  is  of  course 
depressed  and  elevated. 

That  the  power  of  movement  lies  exclusively  in  the 
surface  of  the  disc  is  well  shown  in  the  case  of  the 
saddle-shaped  disc  of  Orchis  pyramidalis  ;  for  whilst  it 
was  held  under  water  I  removed  the  attached  caudicles 
and  the  layer  of  viscid  matter  from  the  inferior  surface, 
and  immediately  that  the  disc  was  exposed  to  the  air 
the  proper  contraction  ensued.  The  disc  is  formed  of 
several  layers  of  minute  cells,  which  are  best  seen  in 
specimens  that  have  been  kept  in  spirits  of  wine, 
for  their  contents  are  thus  rendered  more  opaque.  The 
cells  in  the  flaps  of  the  saddle  are  a  little  elongated. 
As  long  as  the  saddle  is  kept  damp,  its  upper  surface 
is  nearly  flat,  but  when  exposed  to  the  air  (see  fig.  3, 


Chap.  IX.        MOVEMENTS  OF   THE   POLLINIA.  273 

E,  p.  18)  the  two  flaps  or  sides  contract  and  curl  inwards ; 
and  this  causes  the  divergence  of  the  poUinia.  By  a 
kind  of  contraction  two  valleys  are  likewise  formed  in 
front  of  the  caudicles,  so  that  the  latter  are  thrown 
forwards  and  downwards,  almost  in  the  same  way  as  if 
trenches  were  dug  in  front  of  two  upright  poles,  and 
then  carried  on  so  as  to  undermine  them.  As  far  as  I 
could  perceive,  an  analogous  contraction  causes  the 
depression  of  the  pollinia  in  Orchis  mascula.  With  0. 
hircina  both  pollinia  are  attached  to  a  single  rather  large 
square  disc,  the  whole  front  of  which,  after  exj)osure 
to  the  air,  sinks  down  and  is  then  separated  from  the 
hinder  part  by  an  abrupt  step.  By  this  contraction  both 
pollinia  are  carried  forwards  and  downwards. 

Some  pollinia  which  had  been  gummed  on  card  for 
several  months,  when  placed  in  water,  rose  up  and 
afterwards  underwent  the  movement  of  depression. 
A  fresh  pollinium,  on  being  alternately  damped  and 
exposed  to  the  air,  rises  and  sinks  several  times  alter- 
nately. Before  I  had  ascertained  these  facts,  which 
show  that  the  movement  is  simply  hygrometric,  I 
thought  that  it  was  a  vital  action,  and  tried  vapour 
of  chloroform  and  of  prussic  acid,  and  immersion  in 
laudanum;  but  these  reagents  did  not  check  the 
movement.  Nevertheless,  there  are  some  difficulties 
in  understanding  how  the  movement  can  be  simply 
hygrometric.  The  flaps  of  the  saddle  in  Orchis  pyra- 
midalis  (see  fig.  3,  D,  p.  18)  curl  completely  inwards 
in  nine  seconds,  which  is  a  surprisingly  short  time 
for  mere  evaporation  to  produce  an  effect  ;*  and  the 


*  This  fact  does  not  now  appear  awn  of  Stipa  twists  and  untwists 

to  me  so  surprising  as  it  feruieriy  when  exposed  to  dry  and  (iaijjp  uLr. 

did,  for  niY  son  Francis  has  s^liowu  Tliese  movements  being  due,  as 

( '  Transact.  Linn.  Soc'  2nd  series,  he  has  shown,  to  tlie  twisting  and 

But.    vol.    i.    1876,   p.    14i»)   with  untwisting  of  the  separate  cells, 
what  extr  .ordinary  quickno.^s  the 
13 


274  CONCLUDING   REMARKS.  Chap   IX. 

movement  is  apparently  due  to  the  drying  of  the  under 
surface,  although  this  is  covered  with  a  thick  layer 
of  viscid  matter.  The  edges,  however,  of  the  saddle 
might  become  slightly  dry  in  the  nine  seconds.  When 
the  saddle-formed  disc  is  placed  in  spirits  of  wine  it 
contracts  energetically ;  and  this  is  probably  due  to 
the  attraction  of  alcohol  for  water.  When  replaced  in 
water  it  opens  again.  Whether  or  not  the  contraction 
is  wholly  hygrometric,  the  movements  are  admirably 
regulated  in  each  species,  so  that  the  pollen-masses, 
when  transported  by  insects  from  flower  to  flower, 
assume  a  proper  position  for  striking  the  stigmatic 
surface. 

These  various  movements  would  be  quite  useless, 
unless  the  pollinia  were  attached  in  a  uniform  position 
to  the  insects  which  visit  the  flowers  so  as  to  be  always 
directed  in  the  same  manner  after  the  movement  of 
depression  ;  and  this  necessitates  that  the  insects  should 
be  forced  to  visit  the  flowers  of  the  same  species  in 
a  uniform  manner.  Hence  I  must  say  a  few  words 
on  the  sepals  and  petals.  Their  primary  function,  no 
doubt,  is  to  protect  the  organs  of  fructification  in  the 
bud.  After  the  flower  is  fully  expanded,  the  upper 
sepal  and  two  upper  petals  often  continue  the  same 
office.  We  cannot  doubt  that  this  protection  is  of 
service,  when  we  see  in  Stelis  the  sepals  so  neatly  re- 
closing  and  reprotecting  the  flower  some  time  after  its 
expansion ;  in  Masdevallia  the  sepals  are  permanently 
soldered  together,  with  two  little  windows  alone  left 
open ;  and  in  the  open  and  exposed  flowers  of  Bol- 
bophyllum,  the  mouth  of  the  stigmatic  chamber 
after  a  time  closes.  Analogous  facts  with  respect  to 
Malaxis,  Cephalanthera,  &c.,  could  be  given.  But  the 
hood  formed  by  the  upper  sepal  and  two  upper  petals, 
besides  affording  protection,  evidentlv  forms  a  guide, 


Chaf  IX.  CONCLUDING   REMAKKS.  275 

compelling  insects  to  visit  the  flowers  in  front.  Few 
persons  now  doubt  the  correctness  of  C.  K.  Sprengel's 
view,  *  that  the  bright  and  conspicuous  colours  of 
flowers  serve  to  attract  insects  from  a  distance.  Never- 
theless some  Orchids  have  singularly  inconspicuous 
and  greenish  flowers,  perhaps  in  order  to  escape  some 
danger  ;  but  many  of  these  are  strongly  scented,  which 
would  equally  well  serve  to  attract  insects. 

The  labellum  is  by  far  the  most  important  of  the 
external  envelopes  of  the  flower.  It  not  only  secretes 
nectar,  but  is  often  modelled  into  variously  shaped 
receptacles  for  holding  this  fluid,  or  is  itself  rendered 
attractive  so  as  to  be  gnawed  by  insects.  Unless  the 
flowers  were  by  some  means  rendered  attractive,  most 
of  the  species  would  be  cursed  with  perpetual  sterility. 
The  labellum  always  stands  in  front  of  the  rostelium, 
and  its  outer  portion  often  serves  as  a  landing-place 
for  the  necessary  visitors.  In  Epipactis  j^ct^f^stris  this 
part  is  flexible  and  elastic,  and  apparently  compels 
insects  in  retreating  to  brush  against  the  rostelium. 
In  Cypripedium  the  distal  portion  is  folded  over  like 
the  end  of  a  slipper,  and  compels  insects  to  crawl  out 
of  the  flower  by  one  of  two  special  passages.  In  Ptero- 
stylis  and  a  few  other  Orchids  the  labellum  is  irritable, 
so  that  when  touched  it  shuts  the  flower,  leaving  only 
a  single  passage  by  which  an  insect  can  escape.  In 
Spiranthes,  when  the  flower  is  fully  mature,  the  column 
moves  from  the  labellum,  space  being  thus   left   for 


*  This  author's  curious  work,  own  observations,  tliat  his  work 
with  its  quaint  title  of  '  Das  Ent-  contains  an  immense  bo'iy  of 
ieckte  Geheiraniss  der  Natur,'  truth.  Many  years  ago  Robert 
until  lately  was  often  spoken  Brown,  to  whot^e  judprment  all 
lightly  of.  No  doubt  he  whs  an  botanists  defer,  spoke  hipilily  of  it 
enthusiast,  and  perliaps  carried  to  me,  and  remarked  that  only 
some  of  his  ideas  to  an  extreme  those  who  knew  little  of  tlie  nub- 
length.     But  I  feel  sure,  from  my  j<ct  would  laugh  at  him. 


276  CONCLUDING   REMARKS.  Chap.  IX. 

the  introduction  of  tlie  pollen-masses  attached  to  the 
proboscis  of  a  humble-bee.  In  Mormodes  ignea  the 
labellum  is  perched  on  the  summit  of  the  column, 
and  here  insects  alight  and  touch  a  sensitive  point, 
causing  the  ejection  of  the  pollen-masses.  The  la- 
bellum is  often  deeply  channelled,  or  has  guiding 
ridges,  or  is  pressed  closely  against  the  column ;  and 
in  a  multitude  of  cases  it  approaches  closely  enough 
to  render  the  flower  tubular.  By  these  several  means 
insects  are  forced  to  brush  against  the  rostellum.  We 
must  not,  however,  suppose  that  every  detail  of  struc- 
ture in  the  labellum  is  of  use  :  in  some  instances,  as 
with  Sarcanthus,  its  extraordinary  shape  seems  to  be 
partly  due  to  its  development  in  close  apposition  to 
the  curiously  shaped  rostellum. 

In  Listera  ovata  the  labellum  stands  far  from  the 
column,  but  its  base  is  narrow,  so  that  insects  are  led 
to  stand  exactly  beneath  the  middle  of  the  rostellum. 
In  other  cases,  as  in  Stanhopea,  Phalaenopsis,  Gongora, 
&c.,  the  labellum  is  furnished  with  upturned  basal 
lobes,  which  manifestly  act  as  lateral  guides.  In  some 
cases,  as  in  Malaxis,  the  two  upper  petals  are  curled 
backwards  so  as  to  be  out  of  the  way  ;  in  other  cases 
as  in  Acropera,  Masdevallia,  and  some  Bolbophyllums, 
these  upper  petals  plainly  serve  as  lateral  guides,  com- 
pelling insects  to  visit  the  flowers  directly  in  front  of 
the  rostellum.  In  other  cases,  wings  formed  by  the 
margins  of  the  clinandrum  or  of  the  column,  serve  as 
lateral  guides,  both  in  the  withdrawal  of  the  pollinia 
and  in  their  subsequent  insertion  into  the  stigmatic 
cavity.  So  that  there  can  be  no  doubt  that  the  petals, 
sepals  and  rudimentary  anthers  do  good  service  in 
several  ways,  besides  affording  protection  to  the  bud. 

The  final  end  of  the  whole  flower,  with  all  its  parts, 
is  the  production  of  seed ;  and  these  are  produced  by 


Chap.  IX  CONCLUDING    REMARKS.  277 

Orchids  in  vast  profusion.  Not  that  such  profusion 
is  anything  to  boast  of;  for  the  production  of  an  ahnost 
infinite  number  of  seeds  or  eggs,  is  undoubtedly  a  sign 
of  lowness  of  organisation.  That  a  plant,  not  being 
an  annual,  should  escape  extinction,  chiefly  by  the 
production  of  a  vast  number  of  seeds  or  seedlings, 
shows  a  poverty  of  contrivance,  or  a  want  of  some 
fitting  protection  against  other  dangers.  I  was  curious 
to  estimate  the  number  of  seeds  produced  by  some 
few  Orchids  ;  so  I  took  a  ripe  capsule  of  Cephalanthera 
grandijlora,  and  arranged  the  seeds  on  a  long  ruled 
line  as  equably  as  I  could  in  a  narrow  hillock ;  and 
then  counted  the  seeds  in  an  accurately  measured 
length  of  one-tenth  of  an  inch.  In  this  way  the  con- 
tents of  the  capsule  were  estimated  at  6020  seeds,  and 
very  few  of  these  were  bad;  the  four  capsules  borne 
by  the  same  plant  would  have  therefore  contained 
24,080  seeds.  Estimating  in  the  same  manner  the 
smaller  seeds  of  Orchis  maculata,  I  found  the  number 
nearly  the  same,  viz.,  6200 ;  and,  as  I  have  often  seen 
above  thirty  capsules  on  the  same  plant,  the  total 
amount  would  be  186,300.  As  this  Orchid  is  perennial, 
and  cannot  in  most  places  be  increasing  in  number, 
one  seed  alone  of  this  large  number  yields  a  mature 
plant  once  in  every  few  years. 

To  give  an  idea  what  the  above  figures  really  mean, 
I  will  briefly  show  the  possible  rate  of  increase  of  0. 
maculata:  an  acre  of  land  would  hold  174,240  plants, 
each  having  a  space  of  six  inches  square,  and  this 
would  be  just  sufficient  for  their  growth ;  so  that, 
making  the  fair  allowance  of  400  bad  seeds  in  eacli 
capsule,  an  acre  would  be  thickly  clothed  by  the  pro- 
geny of  a  single  plant.  At  the  same  rate  of  increase, 
the  grandchildren  would  cover  a  space  slightly  exceed- 
ing  the  island  of  Anglesea ;    and  the   great    grand- 


278  CONCLUDING   REMARKS.  Chap.  IX. 

children  of  a  single  plant  would  nearly  (in  the  ratio  of 
47  to  50)  clothe  with  one  uniform  green  carpet  the 
entire  surface  of  the  land  throughout  the  globe.  But 
the  number  of  seeds  produced  by  one  of  our  common 
British  orchids  is  as  nothing  compared  to  that  of  some 
of  the  exotic  kinds.  Mr.  Scott  found  that  the  capsule 
of  an  Acropera  contained  371,250  seeds  ;  and  judging 
from  the  number  of  flowers,  a  single  plant  would  some- 
times yield  about  seyenty-four  millions  of  seeds. 
Fritz  Miiller  found  1,756,440  seeds  in  a  single  capsule 
of  a  Maxillaria ;  and  the  same  plant  sometimes  bore 
half-a-dozen  such  capsules.  I  may  add  that  by 
counting  the  packets  of  pollen  (one  of  which  was  broken 
up  under  the  microscope)  I  estimated  that  the  number 
of  pollen-grains,  each  of  which  emits  its  tube,  in  a 
single  anther  of  Orchis  mascula  was  122,400.  Amici* 
estimated  the  number  in  0.  morio  at  120,300.  As 
these  two  species  apparently  do  not  produce  more 
seed  than  the  allied  0.  maculata,  a  capsule  of  which 
contained  6200  seeds,  we  see  that  there  are  about 
twenty  pollen-grains  for  each  ovule.  According  to 
this  standard,  the  number  of  pollen-grains  in  the 
anther  of  a  single  flower  of  the  Maxillaria  which 
yielded  1,756,440  seeds  must  be  prodigious. 

What  checks  the  unlimited  multiplication  of  the 
Orchidese  throughout  the  world  is  not  known.  The 
minute  seeds  within  their  lio-ht  coats  are  well  fitted 
for  wide  dissemination  ;  and  I  have  several  times 
obseiTcd  seedlings  springing  up  in  my  orchard  and  in 
a  newly-planted  wood,  which  must  have  come  from  a 
considerable  distance.  This  was  especially  the  case 
with  EiniKictis  latifolia ;  and  an  instance  has  been  ro 
corded  by  a  good  observer  f  ot  seedlings  of  this  plant 

*  Mohl.  'The  VeiTfta])!.'  Coll,'  f  Mr.  Broe,  in  'T.ouHon*8  Ma^'. 

translated  by  Heiilrcy,  i).  1^6.  ot  Nut.  Hist,'  vol.  ii.  1829,  p.  70. 


Chap.  IX.  CONCLUDING   REMAKES.  279 

appearing  at  the  distance  of  between  eight  and  ten 
miles  from  any  phice  where  it  grew.  Notwithstanding 
the  astonishing  number  of  seeds  produced  by  Orchids, 
it  is  notorious  that  they  are  sparingly  distributed  ;  for 
instance,  Kent  appears  to  be  the  most  favourable  county 
in  England  for  the  order,  and  within  a  mile  of  my 
house  nine  genera,  including  thirteen  species,  grow  ; 
but  of  these  one  alone.  Orchis  morio,  is  sufficiently 
abundant  to  make  a  conspicuous  feature  in  the  vege- 
tation ;  as  is  0.  maculata  in  a  lesser  degree  in  open 
woodlands.  Most  of  the  other  species,  though  not 
deserving  to  be  called  rare,  are  sparingly  distributed ; 
yet,  if  their  seeds  or  seedlings  were  not  largely  de- 
stroyed, any  one  of  them  would  immediately  cover  the 
whole  land.  In  the  tropics  the  species  are  very  much 
more  numerous;  thus  Fritz  Muller  found  in  South 
Brazil  more  than  thirteen  kinds  belonging  to  several 
genera  growing  on  a  single  Cedrela  tree.  Mr.  Fitz- 
gerald has  collected  within  the  radius  of  one  mile  of 
Sydney  in  Australia  no  less  than  sixty-two  species,  of 
which  fifty-seven  were  terrestrial.  Nevertheless  the 
number  of  individuals  of  the  same  species  is,  I  believe, 
in  no  country  nearly  so  great  as  that  of  very  many 
other  plants.  Lindley  formerly  estimated  that  there 
were  in  the  world  about  6000  sjjecies  of  Orchideas, 
included  in  433  genera.* 

The  number  of  the  individuals  which  come  to 
maturity  does  not  seem  to  be  at  all  closely  determined 
by  the  number  of  seeds  which  each  species  produces  ; 
and  this  holds  good  when  closely  related  forms  are 
compared.  Thus  Ophrys  apifera  fertilises  itself  and 
every  flower  produces  a  capsule ;  but  the  individuals 
of  this  species  are  not  so  numerous  in  some  parts  of 


»  •  Gardener's  Cliron.'  1862,  p.  192. 


280  CONCLUDING   REMARKS.  Chap.  IX. 

England  as  those  of  0.  muscifera,  which  cannot  fer- 
tilise itself  and  is  imperfectly  fertilised  by  insects,  so 
that  a  large  proportion  of  the  flowers  drop  off  unim- 
pregnated.  Ophrys  aranifera  is  found  in  large  numbers 
in  Liguria,  yet  Delpino  estimates  that  not  more  than 
one  out  of  3000  flowers  produces  a  capsule.*  Mr. 
Cheeseman  saysf  that  with  the  New  Zealand  Ptero- 
stylis  truUifolia  much  less  than  a  quarter  of  the  flowers, 
which  are  beautifully  adapted  for  cross-fertilisation, 
yield  capsules ;  whereas  with  the  allied  Aeianthus 
sinclairii,  the  flowers  of  which  equally  require  insect- 
aid  for  their  fertilisation,  seventy-one  capsules  were 
produced  by  eighty-seven  flowers ;  so  that  this  plant 
must  produce  an  extraordinary  number  of  seeds  ;  never- 
theless in  many  districts  it  is  not  at  all  more  abundant 
than  the  Pterostylis.  Mr.  Fitzgerald,  who  in  Aus- 
tralia has  particularly  attended  to  this  subject,  remarks 
that  every  flower  of  Thehjmitra  carnea  fertilises  itself 
and  produces  a  capsule ;  yet  it  is  not  nearly  so  common 
as  Aeianthus  fornicatus,  "  the  majority  of  the  flowers 
of  which  are  unproductive.  Phajus  grandifolius  and 
CalantJie  veratrifolia  grow  in  similar  situations.  Every 
flower  of  the  Phajus  produces  seeds,  only  occasionally 
one  of  the  Calanthe,  yet  Phajus  is  rare  and  Calanthe 
common." 

The  frequency  with  which  throughout  the  world 
members  of  various  Orchideous  tribes  fail  to  have  their 
flowers  fertilised,  though  these  are  excellently  con- 
structed for  cross-fertilisation,  is  a  remarkable  fact. 
Fritz  Muller  informs  me  that  this  holds  good  in  the 
luxuriant  forests  of  South  Brazil  with  most  of  the 
Epidendrete,  and  with  the  genus  Vanilla.   For  instance, 


*   'Ult.   Osservaz.  siiUa   Dico-  f    Transact.  New  Zealand  Inst, 

gamia,'  part  i.  p.  177.  vol.  vii.  1875,  p.  351. 


Chap.  IX.  CONCLUDING   REMARKS.  281 

he  visited  a  site  where  Vanilla  creeps  over  almost  every 
tree,  and  although  the  plants  had  been  covered  with 
flowers,  yet  only  two  seed-capsules  were  produced.  So 
again  with  an  Epidendrum,  233  flowers  had  fallen  off 
unimpregnated  and  only  one  capsule  had  been  formed  ; 
of  the  still  remaining  136  flowers,  only  four  had  their 
pollinia  removed.  In  New  South  Wales  Mr.  Fitzgerald 
does  not  believe  that  more  than  one  flower  out  of  a 
thousand  of  Dendrdbium  si:>eciosum  sets  a  capsule ;  and 
some  other  species  there  are  very  sterile.  In  New 
Zealand  over  200  flowers  of  Coryanthes  triloba  yielded 
only  five  capsules ;  and  at  the  Cape  of  Good  Hope  only 
the  same  number  were  produced  by  78  flowers  of  Disa 
grancliflora.  Nearly  the  same  result  has  been  observed 
with  some  of  the  species  of  Ophrys  in  Europe.  The 
sterility  in  these  cases  is  very  difiicult  to  explain.  It 
manifestly  depends  on  the  flowers  being  constructed 
with  such  elaborate  care  for  cross-fertilisation,  that  they 
cannot  yield  seeds  without  the  aid  of  insects.  From 
the  evidence  which  I  have  given  elsewhere  *  we  may 
conclude  that  it  would  be  far  more  profitable  to  most 
plants  to  yield  a  few  cross -fertilised  seeds,  at  the 
expense  of  many  flowei-s  dropping  off  unimpregnated, 
rather  than  produce  many  self-fertilised  seeds.  Profuse 
expenditure  is  nothing  unusual  under  nature,  as  we  see 
with  the  pollen  of  wind-fertilised  plants,  and  in  the 
multitude  of  seeds  and  seedlings  produced  by  most 
plants  in  comparison  with  the  few  that  reach  maturity. 
In  other  cases  the  paucity  of  the  flowers  that  are  im- 
pregnated may  be  due  to  the  proper  insects  having 
become  rare  under  the  incessant  changes  to  which  the 
world  is  subject ;  or  to  other  plants  which  are  more 


♦  ♦  Tho  Effects  of  Cioss  and    Self-fertilisation  in  the  Vegetable 
Kingdom,'  1876. 


282  CONCLUDING  REMARKS.  Chap.  IX. 

highly  attractive  to  the  proper  insects  having  increased 
in  number.  We  know  that  certain  Orchids  require 
certain  insects  for  their  fertilisation,  as  in  the  cases  be- 
fore given  of  Vanilla  and  Sarcochilus.  In  Madagascar 
Angrdecum  sesqui2)edale  must  depend  on  some  gigantic 
moth.  In  Europe  Gypripedium  calceolus  appears  to  be 
fertilised  only  by  small  bees  of  the  genus  Andrena, 
and  Epipactis  latifolia  only  by  wasps.  In  those  cases 
in  which  only  a  few  flow^ers  are  impregnated  owing  to 
the  proper  insects  visiting  only  a  few,  this  may  be  a 
great  injury  to  the  plant ;  and  many  hundred  species 
throughout  the  world  have  been  thus  exterminated  ; 
those  which  survive  having  been  favoured  in  some 
other  way.  On  the  other  hand,  the  few  seeds  which 
are  produced  in  these  cases  will  be  the  product  of 
cross-fertilisation,  and  this  as  we  now  positively  know 
is  an  immense  advantage  to  most  plants. 

I  have  now  nearly  finished  this  volume,  which  is 
perhaps  too  lengthy.  It  has,  I  think,  been  shown  that 
the  Orchideae  exhibit  an  almost  endless  diversity  of 
beautiful  adaptations.  When  this  or  that  part  has  been 
spoken  of  as  adapted  for  some  special  purpose,  it  must 
not  be  supposed  that  it  was  originally  always  formed 
for  this  sole  purpose.  The  regular  course  of  events 
seems  to  be,  that  a  part  which  originally  served  for  one 
purpose,  becomes  adapted  by  slow  changes  for  widely 
different  purposes.  To  give  an  instance :  in  all  the 
Ophrese,  the  long  and  nearly  rigid  caudicle  manifestly 
serves  for  the  application  of  the  pollen-grains  to  the 
stigma,  when  the  pollinia  are  transported  by  insects 
to  another  flower ;  and  the  anther  opens  widely  in 
order  that  the  pollinium  should  be  easily  withdrawn  ; 
but  in  the  Bee  Ophrys,  the  caudicle,  by  a  slight  in- 
crease in  length  and  decrease  in  its  thickness,  and  by 


Chap.  IX.  CONCLUDING   REM AKKS.  283 

the  anther  opening  a  little  more  widely,  becomes 
specially  adapted  for  the  very  ditferent  purpose  of 
self-fertilisation,  through  the  combined  aid  of  the 
weight  of  the  pollen-mass  and  the  vibration  of  the 
flower  when  moved  by  the  wind.  Every  gradation 
between  these  two  states  is  possible, — of  which  we  have 
a  partial  instance  in  0  aranifera. 

Again,  the  elasticity  of  the  pedicel  of  the  poUinium 
in  some  Yandese  is  adapted  to  free  the  pollen-masses 
from  their  anther-cases  ;  but  by  a  further  slight  modi- 
fication, the  elasticity  of  the  pedicel  becomes  specially 
adapted  to  shoot  out  the  pollinium  with  considerable 
force  so  as  to  strike  the  body  of  the  visiting  insect. 
The  great  cavity  in  the  labellum  of  many  Yandeee 
is  gnawed  by  insects  and  thus  attracts  them;  but 
in  Mor modes  ignea  it  is  greatly  reduced  in  size,  and 
serves  in  chief  part  to  keep  the  labellum  in  its  new 
position  on  the  summit  of  the  column.  From  the 
analogy  of  many  plants  we  may  infer  that  a  long 
spur-like  nectary  is  primarily  adapted  to  secrete  and 
hold  a  store  of  nectar ;  but  in  many  Orchids  it  has  so 
far  lost  this  function,  that  it  contains  fluid  only  in  the 
intercellular  spaces.  In  those  Orchids  in  which  the 
nectary  contains  both  free  nectar  and  fluid  in  the  inter- 
cellular spaces,  we  can  see  how  a  transition  from  the 
one  state  to  the  other  could  be  effected,  namely,  by 
less  and  less  nectar  being  secreted  from  the  inner 
membrane,  with  more  and  more  retained  within  the 
intercellular  spaces.  Other  analogous  cases  could  be 
given. 

Although  an  organ  may  not  have  been  originally 
formed  for  some  special  purpose,  if  it  now  serves  for 
this  end,  we  are  justified  in  saying  that  it  is  specially 
adapted  for  it.  On  the  same  principle,  if  a  man  were 
to  make  a  machine  for  some  special  purpose,  but  were 


284  CONCLUDING   REMARKS.  Chap.  IX 

to  use  eld  wheels,  springs,  and  pulleys,  only  slightly 
altered,  the  whole  machine,  with  all  its  parts,  might  be 
said  to  be  specially  contrived  for  its  present  purpose. 
Thus  throughout  nature  almost  every  part  of  each  living 
being  has  probably  served,  in  a  slightly  modified  con- 
dition, for  diverse  purposes,  and  has  acted  in  the  living 
machinery  of  many  ancient  and  distinct  specific  forms. 

In  my  examination  of  Orchids,  hardly  any  fact  has 
struck  me  so  much  as  the  endless  diversities  of  structure, 
— the  prodigality  of  resources, — ^for  gaining  the  very 
same  end,  namely,  the  fertilisation  of  one  flower  by 
pollen  from  another  plant.  This  fact  is  to  a  large  ex- 
tent intelligible  on  the  principle  of  natural  selection. 
As  all  the  parts  of  a  flower  are  co-ordinated,  if  slight 
variations  in  any  one  part  were  preserved  from  being 
beneficial  to  the  plant,  then  the  other  parts  would 
generally  have  to  be  modified  in  some  corresponding 
manner.  But  these  latter  parts  might  not  vary  at  all, 
or  they  might  not  vary  in  a  fitting  manner,  and  these 
other  variations,  whatever  their  nature  might  be,  which 
tended  to  bring  all  the  parts  into  more  harmonious 
action  with  one  another,  would  be  preserved  by  natural 
selection. 

To  give  a  simple  illustration  :  in  many  Orchids  the 
ovarium  (but  sometimes  the  foot-stalk)  becomes  for  a 
period  twisted,  causing  the  labellum  to  assume  the 
position  of  a  lower  petal,  so  that  insects  can  easily 
visit  the  flower;  but  from  slow  changes  in  the  form 
or  position  of  the  petals,  or  from  new  sorts  of  insects 
visiting  the  flowers,  it  might  be  advantageous  to  the 
plant  that  the  labellum  should  resume  its  normal 
position  on  the  upper  side  of  the  flower,  as  is  actually 
the  case  with  Malaxis  2?aludosa,  and  some  species  of 
Catasetum,  &c.  This  change,  it  is  obvious,  might  be 
simply  effected  by  the  continued  selection  of  varieties 


Chap.  IX  CONCLUDING   KEMAKKS.  285 

which  had  their  ovaria  less  and  less  twisted,  but  if 
the  plant  only  afforded  varieties  with  the  ovarium 
more  twisted,  the  same  end  could  be  attained  by  the 
selection  of  such  variations,  until  the  flower  w^as 
turned  completely  round  on  its  axis.  This  seems  to 
have  actually  occurred  with  Malaxis  paludosa,  for 
the  labellum  has  acquired  its  present  upward  posi- 
tion by  the  ovarium  being  twisted  twice  as  much  as 
is  usual. 

Again,  we  have  seen  that  in  most  Vandese  there  is 
a  plain  relation  between  the  depth  of  the  stigmatic 
chamber  and  the  length  of  the  pedicel,  by  which  the 
pollen-masses  are  inserted ;  now  if  the  chamber  became 
slightly  less  deep  from  any  change  in  the  form  of  the 
column  or  other  unknown  cause,  the  mere  shortening 
of  the  pedicel  would  be  the  simplest  corresponding 
change ;  but  if  the  pedicel  did  not  happen  to  vary  in 
shortness,  the  slightest  tendency  to  its  becoming  bowed 
from  elasticity  as  in  Phalaenopsis,  or  to  a  backward 
hygrometric  movement  as  in  one  of  the  Maxillarias, 
would  be  preserved,  and  the  tendency  would  be  con- 
tinually augmented  by  selection ;  thus  the  pedicel,  as 
far  as  its  action  is  concerned,  would  be  modified  in 
the  same  manner  as  if  thad  been  shortened.  Such 
processes  carried  on  during  many  thousand  generations 
in  various  ways,  w^ould  create  an  endless  diversity  of 
co-adapted  structures  in  the  several  parts  of  the  flower 
for  the  same  general  purpose.  This  view  affords,  I 
believe,  the  key  which  partly  solves  the  problem  of  the 
vast  diversity  of  structure  adapted  for  closely  analogous 
ends  in  many  large  groups  of  organic  beings. 

The  more  I  study  nature,  the  more  I  become 
impressed  with  ever-increasing  force,  that  the  con- 
trivances and  beautiful  adaptations  slowly  acquired 
through  each   part  occasionally  varying  in  a  slight 


286  CONCLUDING   REMARKS.  Chap.  IX 

degree  but  in  many  ways,  with  the  preservation  of  those 
variations  which  were  beneficial  to  the  organism  under 
comjDlex  and  ever- varying  conditions  of  life,  transcend 
in  an  incomparable  manner  the  contrivances  and 
adaptations  which  the  most  fertile  imagination  of  man 
could  invent. 

The  use  of  each  trifling  detail  of  structure  is  far 
from  a  barren  search  to  those  who  believe  in  natural 
selection.  When  a  naturalist  casually  takes  up  the 
study  of  an  organic  being,  and  does  not  investigate 
its  whole  life  (imperfect  though  that  study  will  ever 
be),  he  naturally  doubts  whether  each  trifling  point 
can  be  of  any  use,  or  indeed  whether  it  be  due  to  any 
general  law.  Some  naturalists  believe  that  number- 
less structures  have  been  created  for  the  sake  of  mere 
variety  and  beauty, — much  as  a  workman  would  make 
different  patterns.  I,  for  one,  have  often  and  often 
doubted  whether  this  or  that  detail  of  structure  in 
many  of  the  Orchidese  and  other  plants  could  be  of 
any  service  ;  yet,  if  of  no  good,  these  structures  could 
not  have  been  modelled  by  the  natural  preservation  of 
useful  variations;  such  details  can  only  be  vaguely 
accounted  for  by  the  direct  action  of  the  conditions  of 
life,  or  the  mysterious  laws  of  correlated  growth. 

To  give  nearly  all  the  instances  of  trifling  details 
of  structure  in  the  flowers  of  Orchids,  which  are  cer- 
tainly of  high  importance,  would  be  to  recapitulate 
almost  the  whole  of  this  volume.  But  I  will  recall 
to  the  reader's  memory  a  few  cases.  I  do  not  here  refer 
to  the  fundamental  framework  of  the  plant,  such  as 
the  remnants  of  the  fifteen  primary  organs  arranged 
alternately  in  the  five  whorls ;  for  almost  everyone  who 
believes  in  the  gradual  evolution  of  species  will  admit 
that  their  presence  is  due  to  inheritance  from  a  remote 
parent-form.      Innumerable  facts  with  respect  to  the 


Chap.  IX.  CONCLUDING   REMAKKS.  287 

uses  of  the  variously  shaped  and  placed  petals  and 
sepals  have  been  given.  So  again,  the  importance  of 
as  light  difference  in  the  shape  of  the  caudicle  of  the 
pollinium  of  the  Bee  Ophrys,  compared  with  that  of 
the  other  species  of  the  same  genus,  has  likewise  been 
referred  to ;  to  this  might  be  added  the  doubly-bent 
caudicle  of  the  Fly  Ophrys.  Indeed,  the  important 
relation  of  the  length  and  shape  of  the  caudicle,  with 
reference  to  the  position  of  the  stigma,  might  be  cited 
throughout  many  whole  tribes.  The  solid  projecting 
knob  of  the  anther  in  Epipactis  palustris,  which  does 
not  include  pollen,  liberates  the  pollen-masses  when  it 
is  moved  by  insects.  In  CephalaniJiera  grandiflora,  the 
upright  position  of  the  almost  closed  flower  protects 
the  slightly  coherent  pillars  of  pollen  from  disturb- 
ance. The  length  and  elasticity  of  the  filament  of  the 
anther  in  certain  species  of  Dendrobium  apparently 
serves  for  self-fertilisation,  if  insects  fail  to  transport 
the  pollen-masses.  The  slight  forward  inclination  of 
the  crest  of  the  rostellum  in  Listera  prevents  the 
anther-case  boing  caught  as  soon  as  the  viscid  matter 
is  ejected.  The  elasticity  of  the  lip  of  the  rostellum 
in  Orchis  causes  it  to  spring  up  again  when  only  one 
of  the  pollen-masses  has  been  removed,  thus  keeping 
the  second  viscid  disc  ready  for  action,  which  otherwise 
would  be  wasted.  No  one  who  had  not  studied  Orchids 
would  have  suspected  that  these  and  very  many  other 
small  details  of  structure  were  of  the  highest  importance 
to  each  species ;  and  that  consequently,  if  the  species 
were  exposed  to  new  conditions  of  life,  and  the  structure 
of  the  several  parts  varied  ever  so  little,  the  smallest 
details  of  structure  might  readily  be  acquired  through 
natural  selection.  These  cases  afford  a  good  lesson  of 
caution  with  respect  to  the  importance  of  apparently 
trifling  particulars  of  structure  in  other  organic  beings. 


288  CONCLmTiNG   remarks.  Chap.  IX. 

It  may  naturally  be  inquired,  Why  do  the  Orchideae 
exhibit  so  many  perfect  contrivances  for  their  fertili- 
sation? From  the  observations  of  various  botanists 
and  my  own,  I  am  sure  that  many  other  plants  offer 
analogous  adaptations  of  high  perfection ;  but  it  seems 
that  they  are  really  more  numerous  and  perfect  with 
the  Orchidea3  than  with  most  other  plants.  To  a 
certain  extent  this  inquiry  can  be  answered.  As  each 
ovule  requires  at  least  one,  probably  several,  pollen- 
grains,*  and  as  the  seeds  produced  by  Orchids  are  so 
inordinately  numerous,  we  can  see  that  it  is  necessary 
that  large  masses  of  pollen  should  be  left  on  the  stigma 
of  each  flower.  Even  in  the  Neottese,  which  have 
granular  pollen,  with  the  grains  tied  together  by  weak 
threads,  I  have  observed  that  considerable  masses  of 
pollen  are  generally  left  on  the  stigmas.  This  cir- 
cumstance apparently  explains  why  the  grains  cohere 
in  packets  or  large  waxy  masses,  as  they  do  in  so 
many  tribes,  namely,  to  prevent  waste  in  the  act  of 
transportal.  The  flowers  of  most  plants  produce  pollen 
enouo^h  to  fertilise  several  flowers,  so  as  to  allow  of  or  to 
favour  cross-fertilisation.  But  with  the  many  Orchids 
which  produce  only  two  pollen-masses,  and  with  some  of 
the  Malaxese  which  produce  only  one,  the  pollen  from 
a  single  flower  cannot  possibly  fertilise  more  than  two 
flowers  or  only  a  single  one ;  and  cases  of  this  kind 
do  not  occur,  as  I  believe,  in  any  other  group  of 
plants.  If  the  Orchidese  had  elaborated  as  much 
pollen  as  is  produced  by  other  plants,  relatively  to  the 
number  of  seeds  which  they  yield,  they  would  have 
had  to  produce  a  most  extravagant  amount,  and  this 
would  have  caused  exhaustion.  Such  exhaustion  is 
avoided  by  pollen  not  being  produced  in  any  great 

♦  Gartner,  '  Beitr'age  zur  KenntIli.'^s  der  BcfrucbtiiDg,'  1844,  p.  135. 


Chap.  IX.  CONCLUDING   KEMAKKS.  289 

superfluity  owing  to  the  many  special  contrivances  for 
its  safe  transportal  from  plant  to  plant,  and  for  placing 
it  securely  on  the  stigma.  Thus  we  can  understand 
why  the  Orchidese  are  more  highly  endowed  in  their 
mechanism  for  cross-fertilisation,  than  are  most  other 
plants. 

In  my  work  on  the  "Effects  of  Cross  and  Self 
Fertilisation  in  the  Vegetable  Kingdom,"  I  have  shown 
that  when  flowers  are  cross-fertilised  they  generally 
receive  pollen  from  a  distinct  plant  and  not  that  from 
another  flower  on  the  same  plant ;  a  cross  of  this  latter 
kind  doing  little  or  no  good.  I  have  further  shown 
that  the  benefits  derived  from  a  cross  between  two 
plants  depends  altogether  on  their  differing  some- 
what in  constitution  ;  and  there  is  much  evidence  that 
each  individual  seedling  possesses  its  own  peculiar 
constitution.  The  crossing  of  distinct  plants  of  the 
same  species  is  favoured  or  determined  in  various 
ways,  as  described  in  the  above  work,-  but  chiefly 
by  the  prepotent  action  of  pollen  from  another 
plant  over  that  from  the  same  flower.  Now  with  the 
Orchideae  it  is  highly  probable  that  such  prepotency 
prevails,  for  we  know  from  the  valuable  observa- 
tions of  Mr.  Scott  and  Fritz  Mliller,*  that  with  several 
Orchids  pollen  from  their  own  flower  is  quite  im- 
potent, and  is  even  in  some  cases  poisonous  to  the 
stigma.  Besides  this  prepotency,  the  Orchideae  pre- 
sent various  special  contrivances — such  as  the  pollinia 
not  assuming  a  proper  position  for  striking  the  stigma 
until  some  time  has  elapsed  after  their  removal  from 
the  anthers — the  slow  curving  forwards  and  then  back- 
wards of  the  rostellum  in  Listera  and  Neottia — the 


*  A  full  abe tract  of  these  ob-       Domestication,'  cli.  xvii.  2ud  edit. 
servatioMs  is  given  in  my  ^V;iria-       vol.  ii.  p.  114. 
tion  of  Auimald  and  Plants  under 


290  CONCLUDING   REMARKS.  Ohap.  IX. 

slow  movement  of  the  column  from  the  labellum  in 
Spiranthes — the  dioecious  condition  of  Catasetum — 
the  fact  of  some  species  producing  only  a  single 
flower,  &c. — all  render  it  certain  or  highly  probable 
that  the  flowers  are  habitually  fertilised  with  pollen 
from  a  distinct  plant. 

That  cross-fertilisation,  to  the  complete  exclusion  of 
self-fertilisation,  is  the  rule  with  the  Orchidese,  cannot 
be  doubted  from  the  facts  already  given  in  relation  to 
many  species  in  all  the  tribes  throughout  the  world. 
I  could  almost  as  soon  believe  that  flowers  in  general 
were  not  adapted  for  the  production  of  seeds,  because 
there  are  a  few  plants  which  have  never  been  known  to 
yield  seed,  as  that  the  flowers  of  the  Orchidese  are  not 
as  a  general  rule  adapted  so  as  to  ensure  cross-fertilisa- 
tion. Nevertheless,  some  species  are  regularly  or  often 
self-fertilised;  and  I  will  now  give  a  list  of  all  the 
cases  hitherto  observed  by  myself  and  others.  In  some 
of  these  the  flowers  appear  often  to  be  fertilised  by 
insects,  but  they  are  capable  of  fertilising  themselves 
without  aid,  though  in  a  more  or  less  incomplete 
manner ;  so  that  they  do  not  remain  utterly  barren  if 
insects  fail  to  visit  them.  Under  this  head  may  be 
included  three  British  species,  namely,  CepJialanthera 
graiidiflora,  Neottia  nidus-avis,  and  perhaps  List  era 
ovata.  In  South  Africa  Bisa  macrantha  often  fertilises 
itself ;  but  Mr.  Weale  believes  that  it  is  likewise  cross- 
fertilised  by  moths.  Three  species  belonging  to  the 
Epidendrese  rarely  open  their  flowers  in  the  West 
Indies ;  nevertheless  these  flowers  fertilise  themselves, 
but  it  is  doubtful  whether  they  are  fully  fertilised, 
for  a  large  proportion  of  the  seeds  spontaneously  pro- 
duced by  some  members  of  this  tribe  in  a  hothouse 
were  destitute  of  an  embryo.  Some  species  of  Dendro- 
bium,  judging   from  their   structure   and  from   their 


Chap.  IX.  CONCLUDING   EEMAEKS.  291 

occasionally   producing    capsules    under    cultiyation, 
likewise  come  under  this  head. 

Of  species  which  regularly  fertilise  themselves  with- 
out any  aid  and  yield  full-sized  capsules,  hardly  any 
case  is  more  striking  than  that  of  Oplirys  apifera,  which 
was  advanced  by  me  in  the  first  edition  of  this  work. 
To  this  case  may  now  be  added  two  other  European 
plants,  Orcliis  or  Neotinea  intada  and  Upipactis  viricli- 
tlora.  Two  North  American  species,  Gymnadenia 
tridentata  and  Platanthera  hyperhorea  appear  to  be  in 
the  same  predicament,  but  whether  when  self-fertilised 
they  yield  a  full  complement  of  capsules  containing 
good  seeds  has  not  been  ascertained.  A  curious 
Epidendrum  in  South  Brazil  which  bears  two  additional 
anthers  fertilises  itself  freely  by  their  a  id  ;  and  Dendro- 
hium  cretaceum  has  been  known  to  produce  perfect  self- 
fertilised  seeds  in  a  hothouse  in  England.  Lastly, 
Spiranthes  australis  and  two  species  of  Thelymitra, 
inhabitants  of  Australia,  come  under  this  same  head. 
No  doubt  other  cases  will  hereafter  be  added  to  this 
short  list  of  about  ten  species  which  it  appears  can 
fertilise  themselves  fully,  and  of  about  the  same 
number  of  species  which  fertilise  themselves  imper- 
fectly when  insects  are  excluded. 

It  deserves  especial  attention  that  the  flowers  of  all 
the  above-named  self-fertile  species  still  retain  various 
structures  which  it  is  impossible  to  doubt  are  adapted 
for  insuring  cross-fertilisation,  though  they  are  now 
rarely  or  never  brought  into  play.  We  may  therefore 
conclude  that  all  these  plants  are  descended  from 
species  or  varieties  which  were  formerly  fertilised  by 
insect-aid.  Moreover,  several  of  the  genera  to  which 
these  self-fertile  species  belong,  include  other  species, 
which  are  incapable  of  self-fertilisation.  Thelymitra 
offers  indeed  the  oulv  instance  known  to  me  of  two 


2-92  CONCLUDING   REMARKS.  Chap.  IX. 

species  within  the  same  genus  which  regularly  ferti- 
lise themselves.  Considering  such  cases  as  those  of 
Ophrys,  Disa,  and  Epidendrum,  in  which  one  species 
alone  in  the  genus  is  capable  of  complete  self-ferti- 
lisation, whilst  the  other  species  are  rarely  fertilised 
in  any  manner  owing  to  the  rarity  of  the  visits  of 
the  proper  insects; — bearing  also  in  mind  the  large 
number  of  species  in  many  parts  of  the  world  which 
from  this  same  cause  are  seldom  impregnated,  we  are 
led  to  believe  that  the  above-named  self-fertile  plants 
formerly  depended  on  the  visits  of  insects  for  their 
fertilisation,  and  that  from  such  visits  failing  they  did 
not  yield  a  sufficiency  of  seed  and  were  verging  towards 
extinction.  Under  these  circumstances  it  is  probable 
that  they  were  gradually  modified,  so  as  to  become 
more  or  less  completely  self-fertile;  for  it  would 
manifestly  be  more  advantageous  to  a  plant  to  pro- 
duce self-fertilised  seeds  rather  than  none  at  all  or 
extremely  few  seeds.  Whether  any  species  which  is 
now  never  cross-fertilised  will  be  able  to  resist  the 
evil  effects  of  long-continued  self-fertilisation,  so  as  to 
survive  for  as  long  an  average  period  as  the  other 
species  of  the  same  genera  which  are  habitually  cross- 
fertilised,  cannot  of  course  be  told.  But  0])lirys  a^ifera 
is  still  a  highly  vigorous  plant,  and  Gyninadenia  triden- 
tata  and  Platanthera  hyperhorea  are  said  by  Asa  Gray 
to  be  common  plants  in  North  America.  It  is  indeed 
possible  that  these  self-fertile  species  may  revert  in 
the  course  of  time  to  what  was  undoubtedly  their 
pristine  condition,  and  in  this  case  their  various  adap- 
tations for  cross-fertilisation  would  be  again  brought 
into  action.  We  may  believe  that  such  reversion  is 
possible,  when  we  hear  from  Mr.  Moggridge  that 
Ophrys  scolopax  fertilises  itself  freely  in  one  district 
of  Southern   France  without  the  aid  of  insects,  and 


CiiAP.  IX.  CONCLUDING  BEMARKS.  293 

is   completely   sterile   without    such   aid    in  another 
district. 

Finally,  if  we  consider  how  precious  a  substance 
pollen  is,  and  what  care  has  been  bestowed  on 
its  elaboration  and  on  the  accessory  parts  in  the 
Orchideae, — considering  how  large  an  amount  is 
necessary  for  the  impregnation  of  the  almost  innumer- 
able seeds  produced  by  these  plants, — considering  that 
the  anther  stands  close  behind  or  above  the  stigma, 
self-fertilisation  would  have  been  an  incomparably 
safer  and  easier  process  than  the  transportal  of  pollen 
from  flower  to  flower.  Unless  we  bear  in  mind  the 
good  effects  which  have  been  proved  to  follow  in  most 
cases  from  cross-fertilisation,  it  is  an  astonishing  fact 
that  the  flowers  of  the  Orchidese  should  not  have  been 
regularly  self-fertilised.  It  apparently  demonstrates 
that  there  must  be  something  injurious  in  this  latter 
process,  of  which  fact  I  have  elsewhere  given  direct 
proof.  It  is  hardly  an  exaggeration  to  say  that  Nature 
tells  us,  in  the  most  emphatic  manner,  that  she  abhors 
perpetual  self-fertilisation. 


INDEX 


BRO"WN. 


At'tsras  anthropophora,  26;    pollen- 

Battersby,  Dr.,  obh'gations  to,  106 

tubes,  258 

Buuer,    Mr.,    on    pollen-grains     in 

longibracteafa,  2G 

Cephalanthera,  80,  82  ;  on  pollen- 

,  monstrous  flowers,  255 

masses  of  Bletia,  148 

Acianthus  exsertus.  90 

B:e  Ophrvs,  52 

fornicatus,  90,  280 

Beer,  J.  G.,  on  Catasetum,  197 ;  on 

Sinclair  a,    90;    fertil-sed     by 

Cycnoclies,  224 

insects,  280 

Bees  wifcii  attached  pollinia,  80 

Acontia  luduosa  with  polleii-iuassir  s. 

Belt,  Mr.,  on   Aiigrxcxiia   sesquipe- 

31 

dale,  165 

Aa-opera,    pnllinia    of,    154,    156; 

Benthaiu   on   monstrous   flowers  of 

upper  petals,  276 

( hchis  pyramidalis,  88 

loddiqes/i,  IGG 

Inid's-ueot  Orchis,  125 

lufeola,    16G;    vessels  of,  289 

Bolbophyllicm,   274 ;    upper    petals, 

Adaptations,  how  far  special,  2G7; 

276 

diversity  (^f,  282 

barbigerttm,  138 

Aerides,  movement  of  pollinia,  l^Q; 

secretion  of  nectar,  2G5 

cupreum,     137 ;     nectary    of, 

cornutum,  2  Go 

2G5 

rhizoplwrx,  137 

Bonatea  speciosa,  71,  76 ;  vessels  of. 

Amici,  on  number  of  poUen-giains 

244 ;    modified     structure,     264 ; 

in  Orchis  morio,  278 

candicln,  361 

Anderson,  Mr.,  on  Dendrobium,H2  ; 

Bond,  Mr.  F.,  on   moths  with   at- 

on the  Epidendrea,  147 

tached   pollinia,   30;   obligations 

AngriBcum,  viscid  matter  in,  251 

to,  72,  75 

distichum,  154 

Eractese,  secreting  nectar,  266 

Brasaia,  movement  of  pollinia,  156 

sesquipedale,    154,     162,   282; 

Bree,    Mr.,   on   seed   of  Euipactu 

nectary  of,  265 

latif alia,  278 

Antennae  of  the  rostellura  of  Cala- 

Brongiiiart,    M.,    on     secretion    of 

setum,  184,  187 

nectar,  41;   on   Catasetum,    196; 

Anthers,  rudimentary,  240 

spiral  vessels  in  Orchids,  285;  on 

Apostasia,  248 

Uropedium,  240 

Arethusex,  80 

Broun,   Prof.,   on   Stanhnpea   devo- 

Auricles,   or  papillaj,  rudimentary, 

niensis,  171 ;  classification  of  or- 

241, 242 

ganic  beings,  264 

Brown, C, on  Sobral  a  macranfha,9l 

Babington,  Prof.,  on  the  rostclluni, 

,  Piobeit,  on  the  fertilisation  of 

255 

Orchids,  3  ;    viscidity  of  stigma^ 

Baillon,  M.,  on  Cataseium,  191 

13;  Ophrys  ap/fera,  54;  utriculi 

Barkeria,  146. 

of  the  stigma,  202  ;  homologies  of 

Bateman,  Mr.,  obligations  to,  105, 

Orchids,  234,  235,  237 ;  rostellum 

162;   on  Ci/cnoches,  224. 

of  Orchids,  247  ;   Apostasia,  248 ; 

BUTTEKFLIES. 


INDEX. 


DEXDKOBIUM. 


295 


polL-n-tubes,     258  ;     Sprengel's 

work,  275 
Biitteifiies  with  attached  polliuia, 

31 
Butterfly  orchis,  69 
,  Itsser,  73 

Caladenia  dimorpha,  89 

Cahkna.  89 

Calanthe  dominii,  161 

vtasuca,    structure  of    flower, 

161 ;  long  nectary,  267,  269 

veratrifolia,  280 

vest  it  a,  162 

Carpi  nter,  Dr.,  on  Myantlms  and 
Caiasetum,  196 

Catasetidx,  178 

Catasetum,  peculiar  rostellum,  256  ; 
labellum,  270 

callosum,  192,  195 

luridum,  191 

mentosmn,  206 

planieeps,  193 

saccatum,  structure  of  flower, 

180-185;  vessels  of,  239 

tabulare,  192 

tridentatmn,      structure      of 

flower,  191 ;  three  forms  on  the 
isame  plant,  196;  a  male  orchid, 
197;  vessels  of,  289;  peculiar 
form  of  rostellum,  256;  nectar- 
receptacle,  269 

Citttleya,  structure  of  flower,  143- 
148 ;  vessels  of,  239 ;  nectary, 
265 

crispa,  147 

Caudicles  of  pollinia  in  the  Vandex, 
152  ;  development  of,  252 ;  struc- 
ture, 260,  261 

Cephalantliera.  number  of  seeds,  277 

ensifolia,  86 

grandtflora,  structure  of  flower, 

80-86 ;  vessels,  239,  242  ;  change 
of  colour  in  viscid  secretion,  249 ; 
pollen,  259 ;  lubellum,  269  ;  num- 
ber of  seed,  277;  upright  position 
of  flower,  287 ;  partially  self-fer- 
tile, 290 

Cheeseraan,  Mr.,  on  Pterostijlis 
trullifoUa,  88 ;  Acianthus  sin- 
cldirii,  90  ;  imp  rfect  fertilisation 
of  Fterostylis,  280 

Chijsis,  146 

Ci<-rhiea,  contracted  stigma,  171 


Clinandrum,  the,  241 

Ccelogyne  cristata,  146 

ConjantJies,  90,  173  ;  nectary,  232 ; 
secretion  of  nectar,  2(i5 

Jieldingii,  175 

macrantha,  175 

speciosa,  structure  of  flower, 

174 

triloba,  partially  self-sterile,  281 

Cruger,  Dr ,  on  the  Epidendre<e, 
147;  Gongora  maculata,  168; 
StanJiopea,  171;  Coryanthes,  173; 
C.  macrantha,  175 ;  Catasetum, 
197,  200 ;  female  polleu-mas«es, 
202  ;  Selenipedium  palmifoUam, 
232;  homologies  in  Orchids,  235  ; 
bees  gnawing  the  labellum,  270 

Cycnoches  egertonianum,  224 

ventricosum,  structure  of  flower, 

220-224 

Cymbidium  giganteum,  155 :  pol- 
linia, 252,  260;  modification  of 
form,  263 

Cypripedium,  structure  of  flower, 
226 ;  secretion  from,  229  ;  pollen, 
262 ;  labellum,  275 

acaule,  229 

barbatum,  vessels  of,  239 

caJceolus,    229-231  ;    fertilised 

only  by  small  bees,  282 

candidum,  235 

pubescens,  229,  230 

piirpuratuiny  vessels  of,  239 

Cyrtostylis,  90 

Darwin,  Francis,  on  the  movemeut 
of  the  awn  of  Stipa,  273 

,  George,  insects  fertilising  iZer- 

minium  monorchis,  61 ;  Gymna- 
denia  conopsea,  67 

,  William,  on  Epipactis  palustris, 

99,  100 

Delpino  on  insects  being  deceived  by 
the  presence  of  a  nectary  not  con- 
taining neetar,  41  ;  sterility  of 
Spider  Ophrys,  50,  51 ;  Cephulan- 
thera  ensifolia,  86 ;  movements  of 
pollinia,  155;  fertilisation  of  C(//;r»- 
pedium  calce.olus,  231  ;  imi)erf(ct 
fertilisation  of  Ophrys  arani/cra 
in  Liguria,  280 

Dendrobium,  length  of  anther,  2S7 

bigibbum,  142 

cretaceuni,  142,  291 


296 


DENDROBIUM. 


INDEX. 


HABENAKIA. 


Dendrohium  chrysanthum,  structure 
of,  138-142;  nectary,  2G5 

formosuin,  142 

speciosum,  partially  sterile,  281 

tortile,  142 

Descent,  lines  of,  262-265 

Dickie,  Prof.,  obligations  to,  124 

Disa,  secretion  of  nectar,  265 

cornuta,  78 

grandijiora,  77  ;  partially  self- 
sterile,  281 

macro ntha^  78  ;  partially  self- 
fertile,  290 

Disc,  viscidity  of,  in  the  Ophrese., 
43  ;  in  Catasetum,  190  ;  double  in 
the  Ophrex,  254  ;  of  Gymnadt-nia 
conopsea,  272 

Disperis,  secretion  of  nectar,  265 

Ducbartre,  M.,  on  Catasetum  and 
Myanthus,  196 

Dver,  Mr.  Thiselton,  obligations  to, 
175 

Ejiidendrex,  142;  few  teed  capsules 
produced,  281 

Epidendrum  cochleatum,  viscid  se- 
cretion of,  249 

florihundum,  146;  vi&cid  se- 
cretion, 249 

glaucum,  146 

Epipactis,  vessels  of,  239 ;  viscid 
iQiitter,  251 

latifolia,  100, 101;  pollen,  259  ; 

lerlilised  only  by  wasps,  282; 
use  of  knob  f)f  anther,  287 

microphylla,  102 

palustris,   structure  of  flower, 

93-100  ;  labellum.  275 

purpuratu,  1 02 

ruh,ginosa,  102 

viridifioT'i^     102 ;     self-fertile, 

291 

Epipogium  gmelini,  1 03 

Eulophia  viridis,  156 ;  nectary  of, 
269 

Evelyna,  nectary  of,  265 

carivata,  Hi) ;  vessels  of,  239; 

clinandrum,  241 

Farrer,   T.   H.,   obligations  to,  46; 

on   Bee   Ophrys,    55 ;    Feristylis 

viridis,  63 
Ferlilisation,  summary  on.  290 
I'^ertiLty  of  KUj^lish  Orchids  iVS 


Fitzgerald,  E.  D.,  on  Pterostylis 
longifolia,  89 ;  Caladenia  dimor- 
pha,  89 ;  Acianthus  fornicatus, 
and  exsertus,  90 ;  Vanilla  aroma- 
tica,  91 ;  Spiranthes  australis,  1]  5 ; 
Thelyniitra  Garnea  and  longifolia, 
127 ;  numbers  of  Orchideee  col- 
lected near  Sydney,  279 ;  self- 
fertilisation  of  Thelymitra  carnea, 
280  ;  Dendrohium  speciosum,  281 

Flowers,  use  of  external  envelopes, 
274 

Fly  Ophrys,  46 

Frog  Orchis,  structure  of  flower,  62 ; 
secretion  of  nectur,  63 

G'  I  leandra  funkii,  155 

Gartner  on  viscid  matter  of  stigma, 

249;    pollen-grains    in    Orchids, 

288 
Gerard,  M.  INI.,  pollinia  adhering  to 

longicoru  beetle,  16 
Glossodia,  237 
Gongora,  labellum  of,  276 

atro-purpurea,  169 

macuhita,  168 

trunC'ita,  169 

Goodyera,  vessels  of,  239 ;  caudicle 

in  a  nascent  condition,  260 

discolor,  105 

puhescens.  105 

repens,  103,  105 

Gordon,  Kev.  G.,  obligations  to,  103 
Gosse,  Mr.,  on  self-fertilised  seeds  of 

Ep'dendrew,  147,  148 
Gradation  of  origans,  247 
Giay,   Prof.   Asa,    on   Gymnadenia 

tridentata,  68 ;    Platanthera,  75  ; 

Goodyera  repens,  105 ;  Spiranthes 

gracilis  and  cernua.  111 ;  Cypri- 

pedium,  229,  230,  235 
Gymnadenia,  viscid  matter,  251 

albida,  43,  68 

conopsea,  transplanted,  32 ;  se- 

cietion of  nectar, -i 0, 43 ;  structure 

of  flower,  65 ;  vessels,  238,  239 ; 

rostellum,    255;     movements    of 

pollinia,  271 ;  disc,  272 

odoratissima,  68 

tridentata,  68;  self-fertile,  291 

ITahenaria  hifoJia,  78;  secretion  of 
nectar,  40,  43 ;  viscid  matter,  251 


HABENARIA. 


INDEX 


MORE. 


297 


Uabenaria  ehlorantha,  43, 69 ;  vessels 
of,  239,  244 ;  viscidity  of  exterior 
surfuce,  251 

Hance,  Dr.,  on  Gatasetum,  197 

Herbert,  Dean,  on  Catasetum  luri' 
dum  and  Myanthus,  196 

Herminium  monorchism  59 ;  fertilised 
by  insects,  61 ;  rostelluin,  255 

Hildebrand,  F.,  on  the  ovules  in 
Orchids,  172 

Homologies  of  Orchids,  232 

Hooker,  Dr.,  on  Listera,  3,  115 ; 
lubellum  of  Galxna,  89;  obliga- 
tions to,  115,  128,  244;  spiral 
vessels  in  Orchids,  235;  varia- 
bility of  the  labellum  of  Orchids, 
238 ;  on  the  rostellum,  254 

Horwood,  Mr.,  assistance  from,  129 

Insects,  frequency  of  visits  to  Or- 
chids, 33;  attracted  by  bright 
colours,  275 

Irmisch  on  Epipogium,  103 ;  Neottia 
nidus-avis,  125 ;  flower-bud  of  Cy- 
pripedium,  240 

Kriinitz,  secretion  of  nectar  by 
Orchis,  36 

Kurr,  on  Orchids  secreting  nectar, 
38;  secretion  from  hairs  in  Cy- 
pripedium  calceolus,  229;  nectar 
secreted  from  bracteae,  266 

Labellum  easily  vibratile,  138 ;  cup 
of,  not  secreting  nectar  in  the 
Vandex,  269;  excrescences  on, 
269 ;  gnawed  by  insects,  270;  its 
importance  to  the  flower,  275  ;  of 
Sarcanthus,  276 

Ladies'  slipper,  227 

tresses,  106 

Lxlia,  146 

cinnabarina,  148 

Lepidoptera  with  attached  poUinia, 
30,31 

Leptotes,  14b 

Lindley,  Dr.,  obligations  to,  129; 
arrangement  of  Orchids,  128 ;  on 
forms  of  Catasetum,  197  ;  of  Cyc- 
noches,  224 ;  homologies  of  Orchids, 
235;  on  the  number  of  genera 
and  species,  279 

Link  on  homologies  of  Orchids,  235, 
238 

14 


Liparis  pendula,  vessels  of,    239; 

clinandrum,  241 
Listera,  viscid  matter,  251;   crest 

of  rostellum,  287 

cor  data,  124 

ovata,  structure   of,  115-124; 

labellum,  276 
Lycaste  skinneriij  155;    pollen   of 

260 

Malaxess,  128 

Malaxis,  viscid  matter,  251 ;  upper 
petals,  276 

paludosa,    transplanted,    32 ; 

structure  of  flower,  129-135; 
vessels,  239,  241;  clinandrum, 
241;  pollen-tubes,  258;  position 
of  labellum  afi'ected  by  ovarium, 
284 

Maiden,  Kev.  B.  S.,  obligations  to, 
35,64 

Male  flowers  of  Catasetum,  198 

Marantaceai,  238 

MarshaD,  Mr.,  on  sterility  of  trans- 
planted Orchids,  32;  Hahenaria 
ehlorantha,  72 

Masdevallia,  clinandrum  of,  241 ; 
sepals,  274  ;  upper  petals,  276 

fenestrata,  135,  136,  142 

Maxillaria,  movements  of  pollinia, 
156;  number  of  pollen-grains  in 
anther,  278 

ornithorhyncha,  movement  of 

pollinia,  157,  159 

Megaclinium  falcatum,  labellum  of 
138 

Me'niere  M.,  on  insects  visiting  Or- 
chids, 30  ;  secretion  of  nectar  by 
Coryanthesj  173 ;  movement  of 
Catasetum,  187,  191 ;  the  nectar- 
receptacle,  269 

Minrostylus  rhedii,  132,  135 

Miltonia  clowesii,  pollinia  of,  154, 
155 

Modifications  in  Oichids,  246 

Moggridge,  J.  Traherne,  on  Ophrys 
scolopax,  52, 292 ;  Ophrys  apifera, 
56,  58,  59 ;  flowering  of  the 
Ophrex,  59 

Monachanthus  viridis,  196,  197, 198, 
201 

More,  Mr.  A.  G.,  on  fertility  of  Bee 
Ophrys,  55  ;  Epipactis  yalastris, 
39,  97,  99 ;  obligations  to,  106 


298 


MORMODES. 


INDEX. 


Monnodes  ignea,  structure  of  flower, 
208-219;  viscid  secretion,  249; 
use  of  labellum,  276,  283 

luxata,  219 

Morren,  on  Vanilla  ar.tmatica,  91 

Moths  with  attached  pollinia,  21, 
30,  31 ;  intellect  of,  37 

Movements  of  pollinia,  271 

Miiller,  Fritz,  on  Epidendrex,  148; 
polliuium  of  Ornithocephalus,  159, 
IGO;  Sphinx  moth,  163;  con- 
tracted stigma,  171,  172  ;  ovules 
of  Epidendrex  and  Vandex,  173  ; 
Catasetum  mentosum,  206;  brac- 
teso  of  the  Oncidium  secreting 
nectar,  266 ;  labellum  gnawed  by 
insects  271 ;  number  of  seeds  in 
capsule  of  Maxillaria,  278  ;  num- 
ber of  Orchideae  in  South  BrazU, 
279 ;  the  orchideous  tribes  failing 
to  be  fertilised,  280 ;  prepotency 
of  pollen,  289 

,  Hermann,  on  fertilisation  of 

Orchis  mascula,  13 ;  bees  visiting 
the  flowers  of  Orchis  latifolia, 
16 ;  Nigritella  angustifolia,  27  ; 
fertilisation  of  Orchids,  29;  in- 
sects puncturing  laburnum  flow- 
ers, 41 ;  Gymnadenia  odoratis- 
sima,  68 ;  Habenaria  hifolia 
and  chlorantha,  74;  E'pipactis 
ruhiginosa,  microphylla,  and  viri- 
dijiora,  102  ;  Neottia  nidus-avis, 
125;  Oypripedium  calceolus,  231; 
secretion  of  nectar,  267 

Musk  Orchis,  structure  of  flower, 
59 

Myanthus  haroatus,  192,  199,  203; 
quite  sterile,  205 

Nectar,  secretion  of,  by  British 
OphreaB,  37,  39 ;  in  foreign  Or- 
chids, 229  ;  from  bractese,  229 

Nectary  cut  off  to  test  the  intel- 
lect of  moths,  37 ;  length  of,  in 
Angrxcum  sesquipedale,  265 

Neotinia  intacta,  27,  291 

Neottex,  93 ;  vessels  of,  241 

Neottia  nidus-avis,  125 ;  pollen- 
tubes,  258 ;  partially  self-fertile, 
290 

Nevill,  Lady  Dorothy,  oUigations 
to,  129 

Nicotiana,  stigma  cf,  249 


Nigritella  angustifolia,  27 
Notylia,  contracted  stigma,  171 

Odontoglossum,  156 

Oliver,  Prof.,  obligations  to,  129 

Oncidium,  pollinia,  153,  156,  158; 
vessels  of,  239 ;  viscidity,  251 ; 
bractese  secreting  nectar,  266 

unguiculatum,  development  of 

caudicles,  252 

Ophrex,  6 ;  vessels  of,  241 

Ophrys  apifera,  structure  of  flower, 
52  ;  fertility  of,  54-58  ;  pollen, 
259 ;  self-fertilisation,  279,  291 

arachnites,  51 

aranifera,  50 ;  imperfect  fer- 
tilisation, 280 

muscifera,    transplanted,    32 ; 

structure,  45 ;  fertility,  49 ;  self- 
sterile,  imperfectly  fertilised  by 
insects,  280 

scolopax,  52,  292 

Orchidex,  moditications  in,  246 

Orchis  fuscaj  15  ;  imperfect  fertili- 
sation, 35 ;  secretion  of  nectar,  37 

hircina,  25 ;  nectary,  39;  move- 
ment of  pollinia,  273 

latifolia,  15  ;  imperfect  fer- 
tilisation, 35 ;  secretion  of  nectar, 
37 ;  two  distinct  discs,  255 

maculata,  15, 34 ;  transplanted, 

32 ;  imperfect  fertilisation,  35  ; 
secretion  of  nectar,  37,  39;  two 
distinct  discs,  255 ;  rostellum, 
255 ;  number  of  seeds,  277.  278  ; 

Orchis  mascula,  structure  of  flowt-r, 
6;  movement  of  pollinia,  273  ; 
number  of  pollen-grains,  278 

militaris,  sterility  of,  36 ;  se- 
cretion of  nectar,  37 

morio,  15,  128;  fertility  of,  in 

cold  season,  33;  secretion  of 
nectar,  37,  39 ;  number  of  pollen- 
grains,  278 

pyramidalis,     structure      of 

flower,  16 ;  movements  of  pollinia, 
21,  272,  273  ;  fertility  in  diflerent 
stations,  34;  secretion  of  nectar, 
37,  39 ;  monstrous  flowers,  38 ; 
single  disc,  254 ;  rostellum,  256 ; 
pollen-grains,  260,  261 ;  contriv- 
ances for  its  fertilisation,  264 

ustulata,  25 

Organs,  gradation  of,  247 


0RXITH0CEPHALU3 


INDEX. 


Srr.ENGEL. 


299 


Oniiihocephalus,  160 
Ovai'ia  of  Orchids,  284 
Oxeuden,  Mr.  G.  C,  obligations   to, 
25 ;  ou  Epipactis  purpurata,  102 

Parfitt,  Mr.,  on  attached  pollinia,  31 
Paiker,  Mr.  R.,  obligatious  to,  129 
Pedicel  of  pollinium,  253 ;  elasticity 

of,  283 
Percv,  Dr.,  analysis  of  labellura  of 

W'arrea,  270 
Veridylus  viridis,  secretion  of  nectar, 

43,  63  ;  rostollnni,  255 
Petals,  nsr>s  of,  274 
riiaius,  146 

grandifolius,  280 

Fli(danopx,is,    viscidity    of    stijrnia, 

153;   movement  of  pollinia,  159; 

labellnm,  276 

amahilis,  159 

grandijiora,  150 ;  projection  of 

lab'ellum,  269 
riatanthera,  75 

chlorantha,  69 

dilatata,  77 

flava,  76,  77 

■ hookeri,  75 

• hyperborea,  76;  self-fertile,  291 

Fleurotliallis  ligulata,  135 

■ prolifera,  135 

Pogonia  ophioglossoides,  86 
Poilen-massps,  rudimentary  in  Mono- 

chanthus,  201 ;  gradation  of,  257, 

2S8 
Pollea-tubes   emitted   from   anther, 

258 
Pollinia,   movements  of,   in   Orchis 

mascula,    12-15;    in  0.  pyrami- 

dalis,  21 ;   of  the   Vandex,  154 ; 

of   Catasetum,  ejection    of,    184; 

attachment    to    rostellum,    251 ; 

gradation,  2.i7;  movements,  271 
f'terostylis,  nectary  of,  232 

longiflora,  87,  89 

trullifolia    86,  88  ;   imperfect 

fertilisation  in  New  Zealand,  280 

Rodger?,  Mr.,  obligations  to,  129 ; 
on  Myanthus  and  Monochanthus, 
196 ;  tecretion  of  nectar  in  Or- 
chids, 265  ;  in  Vanilla,  266 

liodrignezia  secunda,  159 

suavcolens,  m<»vemcnt  of  pol- 
linia, 156,  159 


Rohrbadi,  Dr.,  on  Epipogium  gmc' 
lini,  103 

Rostellum,  a  single  organ  in  the 
OphrecB,  45 ;  of  the  Vandex, 
150;  aborted,  242;  gradation  of, 
247 ;  of  Apostasia,  248  ;  diversity 
of  structure,  250 ;  crest  of,  in 
the  Ophrex,  255 ;  in  Catasetum, 
256 

Rucker,  Mr.,  obligations  to.  129, 
ISO,  192,  208 

Saccolahium,   viscidity   of    stigma, 

153,  156 
Saint-Hilaire,  A.  de,  on  pollen  of 

Orchids.  259 
Sarcanthus,  labellura  of,  276 

parishii,  142 

teretif alius,   pollinia    of,   154, 

156;  viscidity,  268 
Scheinsafthlunien,  37 
Schomburgk,  Sir  R.,  on  Catasetum, 

196 
Scott,  Mr.,  on  flowers  of  Acropera, 

168,  172  ;  of  Gongora,  169 ;  nec- 

tor-receptacle,   269;    number    of 

seeds  in  capsule  of  Acropiera,  278  ; 

prepotency  of  pollen.  289 
Scudder,   Mr.,  on    Fogonia   ophio- 
glossoides, 86 
Secretion  of  nectar,  36,  229,  265 
Seeds,  production  and  number  of, 

276,  277 
Selenipedium  palmifolium,  232 
Self-fertilisation,  summary  on,  293 
Sepals,  uses  of,  274 
Serapias  cor  dig  era,  27 
Sexes  of  Orchids,  196 
Smith,  Sir  James,  on  position  of 

flowers  in  Malaxis,  1 29 
,  Mr.  G.  E.,  on  bees  visiting 

the  Bee  Oplirys,  55 
Sohralia  macrantha,  91 
Sophronitis,  146 
Spider  Ophrys,  50 
Spiranthes  audralis,  114;  labellnm, 

275 ;  self-fertile,  291 
autumvalis,  structure  of  flower, 

106-114  ;  vessels  of,  239 

cermca,  111 

gracilis.  111 

Sprengel,  C.  K.,  on  fertilisation  of 

Orchis    miliiaris,   36 ;     secretion 

of  nectar  by  Orchis,  36 ;   on  Epi- 


300 


(STAMENS. 


INDEX. 


ZTGOPETM.DM. 


pactis  latifolia,  101;  Lister  a^ 
115,  123  ;  colours  attracting  in- 
sects, 275;  value  of  his  work, 
275 

Stameus  in  Orchids,  242 

Stanhopea,  pollinia  of,  155;  label- 
lum,  276 

devoniensis,  171 

oculata^  171 

Stelis,  use  of  the  sepals,  274 

racemijlora,  135 

Stei  ility  of  English  Orchids,  35 

Stigma,  viscidity  of,  in  the  Vandex, 
152;  utriculi,  197;  gradiitiou, 
248 ;  structure,  249 

Stipa,  movements  of,  273 

Structure,  diversity  of,  282,  285 

Structure,  importance  of  trifling 
details,  286,  287 

Thehjmitra,  self-fertile,  291 

carnea,  127;  self-fertile,  280 

longijiora,  127 

Thomson,    R.    B.,     on      Goodyera 

repens,  105 
Tilley,  H.  A.,  on  Vanilla  aromatica, 

91 
Trevelyan,  Sir  C,  on  Bombtts  with 

attached  pollen-masses  from  Catt- 

leya,  145 
Treviranus      on     the    secretion  of 

nectar,  41 ;  on  Bee  Oplirys,  56 
friraen,  R.,  obligations  to,  40 ;  on 

Bonatea  speciosa,  76,   77 ,   Lfisa 

grandiflara,  77,  78 


Turnbull,  Mr.,  obligations  to,  129 
T  way-blade,  115 

Uropedkim,  240 

UtricuU  of  stigma,  197,  218 

Vandex,  156 

,  structure  of,    149;    pollinia, 

253.  258 
Vanilla  aromatica,  90 
VamlUdex,  90 ;  few  seed  capsules 

produced,  281 
Veitch,  Mr.  J.,  obligations  to,  129, 

180,  220 
Vessels,  spiral,  of  Orchids,  235 
Viscidity  of  disc  in  British  Ophreoo, 

35  ;  in  Catasetum,  190 
of  rostellum  and  stigma,  248, 

249 

Waetcher  on  fertilisation  of  the 
Orchids,  2 

Walker,  Mr.  F.,  obligations  to,  100 

Wallis,  Mr.,  obligations  to,  129 

Warrea,  155  ;  analysis  of  labellura, 
270 

Weale,  J.  Mansell,  on  Habenaria, 
76 ;  Bonatea,  77  ;  Disa  and  Vis- 
peris,  IS;  Disa  macrantha,  2[)i) 

Weddell,  Dr.,  on  hvbrids  of  Aceras, 
26 

Wright,  Mr.  C,  on  the  movement 
of  pollinia,  156 

Zygopetalum  mackaiy  155 


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has  nowhere  swerved  from  his  purpose  of  showing  in  a  clear,  connected,  and  very 
compendious  form,  not  what  Darwin  may  have  meant  or  has  been  charged  with 
meaning,  but  what  he  actually  said." — The  Sun. 

MENTAL  EVOLUTION  IN  ANIMALS.  By  George  J.  Romanes, 
author  of  "Animal  Intelligence."  With  a  Posthumous  Essay  on 
Instinct,  by  Charles  Darwin.     12mo,  cloth,  $2.00. 

"  Mr.  Romanes  has  followed  up  his  careful  enumeration  of  the  facts  of  'Animal 
Intelligence,'  contributed  to  the  'International  Scientific  Series,'  with  a  work 
dealing  with  the  successive  stages  at  which  the  various  mental  phenomena  appear 
in  the  scale  of  life.  The  present  installment  displays  the  same  evidence  of  indus- 
try in  collecting  facts  and  caution  in  co-ordinating  them  by  theory  as  the  former." 
—  The  Athenaeum. 

"■  The  author  confines  himself  to  the  psychology  of  the  subject.  Not  only  are 
his  own  views  Darwinian,  but  he  has  incorporated  in  his  work  considerable  cita- 
tions from  Darwin's  unpublished  manuscripts,  and  he  has  appended  a  posthu- 
mous essay  on  Instinct  by  Mr.  Darwin."— i?os^on  Journal. 

"A  curious  but  richly  suggestive  volume."— iVisw  York Serald. 

PRACTICAL  ESSAYS.  By  Alexander  Bain,  LL.  D.,  author  of 
"  Mind  and  Body,"  "  Education  as  a  Science,"  etc.  ]  2mo,  cloth,  $1.50. 
"The  present  volume  is  in'part  a  reprint  of  articles  contributed  to  reviews. 
The  principal  bond  of  union  among  them  is  their  practical  character.  .  .  .  That 
there  is  a  certain  amount  of  novelty  in  the  various  suggestions  here  embodied,  will 
be  admitted  on  the  most  cursory  perusal."— i^rom  the  Preface. 

THE  ESSENTIALS  OF  ANATOMY,  PHYSIOLOGY,  AND 
HYGIENE.     By  Roger  S.  Tracy,  M.  D.,  Health  Inspector  of  the 
New  York  Board  of  Health ;  author  of  "  Hand-Book  of  Sanitary  In- 
formation for  Householders,"  etc.     (Forming  a  volume  of  Appletons' 
Science  Text-Books.)     12mo,  cloth,  $1.25. 
"Dr.  Tracy  states  in  his  preface  that  his  aim  has  been  'to  compress  within 
the  narrowest  space  such  a  clear  and  intelligible  account  of  the  structnres,  activi- 
ties, and  care  of  the  human  system  as  is  essential  for  the  purposes  of  general 
education.'    And  he  has  so  far  succeeded  as  to  make  his  manual  one  of  the  most 
popularly  interesting  and  useful  text-books  of  its  kind.  .  .  .  The  book  is  excel- 
lently arranged,  the  illustrations  are  admirable."— Boston  Daily  Advertiser. 

New  York:  D-  APPLETON  &  CO.,  1,  3,  &  5  Bond  Street, 


D.  APPLETON  &  00/S  PUBLICATIONS. 

ORIGIN  OF  CULTIVATED  PLANTS.  By  Alphonse  de  Can- 
DOLLE.     12mo.     Cloth,  $2.00. 

"  The  copious  and  learned  work  of  Alphonse  de  Candolle  on  the  '  Orip:in  of 
Ctxltivated  Plants  '  appears  in  a  translation  as  volume  forty-eight  of  '  The  Inter- 
national Scientitic  Series.'  Any  extended  review  of  this  book  would  be  out  of 
place  here,  for  it  is  crammed  with  interesting  and  curious  facts.  At  the  begin- 
ning of  the  century  the  origin  of  most  of  our  cultivated  species  was  unknown. 
It  now  requires  more  than  four  hundred  closely  printed  pages  to  sum  up  what 
is  known  or  conjectured  of  this  matter.  Among  his  conclusions  M.  de  Candolle 
makes  this  interesting  statement :  '  In  the  history  of  cultivated  plants  I  have 
noticed  no  trace  of  communication  between  the  peoples  of  the  Old  and  New 
Worlds  before  the  discovery  of  America  by  Columbus.'  Not  only  is  this  book 
readable,  but  it  is  of  great  value  for  reference."— Aezi;  York  Herald. 

"Not  another  man  in  the  world  could  have  written  the  book,  and  considering 
both  its  intrinsic  merits  and  the  eminence  of  its  author,  it  must  long  remain  the 
foremost  authority  in  this  curious  branch  of  science.  Of  the  247  plants  here 
enumerated,  199  are  from  the  Old  World,  45  are  American,  and  3  unknown.  Of 
these  only  67  are  of  modern  cultivation.  Curiously,  however,  the  United  States, 
notwithstanding  its  extent  and  fertility,  makes  only  the  pitiful  showing  of 
gourds  and  the  Jerusalem  artichoke."— ^os^cm  Literary  World. 

FALLACIES:    A  View  of  Logic  from  the   Practical  Side. 

By  Alfred  Sidgwick,  B.  A.  Oson.     12mo,     Cloth,  %\.^6. 

"  Even  among  educated  men  logic  is  apt  to  be  regarded  as  a  dry  study,  and  to 
be  neglected  in  favor  of  rhetoric;  it  is  easier  to  deal  with  tropes,  metaphors,  and 
words,  than  with  ideas  and  arguments— to  talk  than  to  reason.  Logic  is  a  study; 
it  requires  time  and  attention,  but  it  can  be  made  interesting,  even  to  general 
readers,  as  this  work  by  Mr.  Sidgwick  upon  that  part  of  it  included  in  the  name 
of  'Fallacies'  shows.  Logic  is  a  science,  and  in  this  volume  we  are  taught  the 
practical  side  of  it.  The  author  discusses  the  meaning  and  aims,  the  subject- 
matter  and  process  of  proof,  unreal  assertions,  the  burden  of  proof,  non-sequiturs., 
guess-work,  argument  by  example  and  sign,  the  reductio  ad  absurdum,  and  other 
branches  of  his  subject  ably  and  fully,  and  has  given  us  a  work  of  real  value.  It 
is  furnished  with  a  valuable  appendix,  and  a  good  index,  and  we  should  be  glad 
to  see  it  in  the  hands  of  thinking  men  who  wish  to  understand  how  to  reason  out 
the  truth,  or  to  detect  the  fallacy  of  an  argument."— TA^  Churchman. 

THE  ORGANS  OF  SPEECH,  and  their  Application  in 
the  Formation  of  Articulate  SoundSe  By  Georg  Hermann 
TON  Meyer,  Professor  of  Anatomy  at  the  University  of  Ziirich. 
With  numerous  Illustrations.     12mo.     Cloth,  Sl.'ZS. 

"This  volume  comprises  the  author's  researches  in  the  anatomy  of  the  vocal 
organs,  with  special  reference  to  the  point  of  view  and  needs  of  the  philologist 
and  the  trainer  of  the  voice.  It  seeks  to  explain  the  origin  of  articulate  sounds, 
and  to  outline  a  system  in  which  all  elements  of  all  languages  may  be  co-ordinated 
in  their  proper  place.  The  work  has  obviously  a  special  value  for  students  in 
the  science  of  the  transmutations  of  language,  for  etymologists,  elocutionists, 
and  musicians."— iVe?/;  York  Home  Journal. 

"  The  author's  plan  has  been  to  give  a  sketch  of  all  possible  articulate  sounds, 
and  to  trace  upon  that  basis  their  relations  and  capacity  for  combination." — 
Philadelphia  North  American. 


New  York :  D.  APPLETON  &  CO.,  1,  3,  &  5  Bond  Street 


D.    APPLETON   &   CO/S   PUBLICATIONS, 


Professor  JOSEPH   LE   CONTE'S   WORKS. 

EVOLUTION  AND  ITS  RELATION  TO  RELIGIOUS 
THOUGHT.  By  Joseph  Le  Conte,  LL.  D.,  Professor  of  Geology 
and  Natural  History  in  the  University  of  California.  With  numer- 
ous Illustrations.     12mo.     Cloth,  $1.50. 

"  ]\ruch,  verj'  mucli  has  been  written,  especially  on  the  nature  and  the  evi- 
dences of  evolution,  but  the  literature  is  eo  voluminous,  much  of  it  so  fragment- 
ary, and  most  of  it  so  technical,  that  even  very  intelligent  persons  have  still  very 
vague  ideas  on  the  subject.  I  have  attempted  to  give  (1)  a  very  concise  account 
of  what  we  mean  by  evolution,  (2)  an  outline  of  the  evidences  of  its  truth  drawn 
from  many  different  sources,  and  (3)  its  relation  to  fundamental  religious  beliefs  " 
—Extract from  Preface. 

ELEMENTS  OF  GEOLOGY.  A  Text-book  for  Colleges  and  for 
the  General  Reader.  By  Joseph  Le  Conte,  LL.  D.  With  upward 
of  900  Illustrations.    New  and  enlarged  edition.    8vo.    Cloth,  $4.00. 

"Besides  preparing  a  comprehensive  text-book,  suited  to  present  demands, 
Professor  Le  Conte  has  given  us  a  volume  of  great  value  as  an  exposition  of  the 
subject,  thoroughly  up  to  date.  The  examples  and  applications  of  the  work  are 
almost  entn-ely  derived  from  this  country,  so  that  it  mav  be  properly  considered 
an  American  geology.  We  can  commend  this  work  without  qualification  to  all 
who  desire  an  intelligent  acquaintance  with  geological  science,  as  fresh,  lucid, 
full,  authentic,  the  result  of  devoted  study  and  of  long  experience  in  teaching." 
—Popular  Scieme  Monthly. 

RELIGION  AND  SCIENCE.  A  Series  of  Sunday  Lectures  on  the 
Relation  of  Natural  and  Revealed  Religion,  or  the  Truths  revealed 
in  Nature  and  Scripture.  By  Joseph  Le  Conte,  LL.  D.  12mo. 
Cloth,  $1.50. 

"  We  commend  the  book  cordially  to  the  regard  of  all  who  are  interested  in 
whatever  pertains  to  the  discussion  of  these  grave  questions,  and  especially  to 
those  who  desire  to  examine  closely  the  strong  foundations  on  which  the  Chris- 
tian faith  is  reared." — Boston  Journal. 


SIGHT  :  An  Exposition  of  the  Principles  of  Monocular  and  Binocular 
Vision.  By  Joseph  Le  Conte,  LL.  D.  With  Illustrations.  12mo. 
Cloth,  $1.50. 

"Professor  Le  Conte  has  long  been  known  as  an  original  investigator  in  this 
department :  all  that  he  gives  us  is  treated  with  a  master-hand.  It  is  pleasant  to 
find  an  American  book  that  can  rank  with  the  very  best  of  foreign  books  on  this 
subject."— 2%€  Nation. 


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D.    APPLETON   &    CO/S   PUBLIOATIONS. 


Professor  E.    L.   YOUMANS'S  WORKS. 

THE     HAND-BOOK     OF     HOUSEHOLD     SCIENCE.     A 

Popular  Account  of  Heat,  Light,  Air,  Aliment,  and  Cleansing,  in 
their  Scientific  Principles  and  Domestic  Applications.  12mo.  Illus- 
trated.    Cloth,  $1.75. 

THE     CULTURE     DEMANDED     BY     MODERN     LIFE. 

A  Series  of  Addresses  and  Arguments  on  the  Claims  of  Scientific 
Education.  Edited,  with  an  Introduction  on  Mental  Discipline  in 
Education.     1  vol.,  12mo.     Cloth,  $2.00. 

CORRELATION    AND    CONSERVATION    OF    FORCES. 

A  Series  of  Expositions  by  Scientific  Men.  Edited,  with  an  Intro- 
duction and  Brief  Biographical  Notices  of  the  Chief  Promoters  of 
the  New  Views,  by  Edward  L.  Youmans,  M.  D.  12mo.  Cloth, 
$2.00. 

CONTENTS. 
I.  By  Professor  W.  R..  Grove.     The  Correlation  of  Physical  Forces. 
II.  By  Professor  Helmholtz.     The  Interaction  of  Natural  Forces. 
III.  By  Dr.  J.  R.  Mayer.     1.  Remarks  on  the  Forces  of  Inorganic  Nature. 

2.  On  Celestial  Dynamics. 

3.  On  the  Mechanical  Equivalent  of  Heat. 
rV.  By  Dr.  Faraday.     Some  Thoughts  on  the  Conservation  of  Forces. 

V.  By  Professor  Liebig.     The  Connection  and  Equivalence  of  Forces. 

VI.  By  Dr.  Carpenter.      The  Correlation  of  the  Physical   and  Vital 

Forces. 

"  This  work  is  a  very  welcome  addition  to  our  scientific  literature,  and 
will  be  particularly  acceptable  to  those  who  wish  to  obtain  a  popular  but 
at  the  same  time  precise  and  clear  view  of  what  Faraday  justly  calls  the 
hip-hest  law  in  physical  science,  the  principle  of  the  conservation  of  force. 
Sufficient  attention  has  not  been  paid  to  the  publication  of  collected  mono- 
graphs or  memoirs  upon  special  subjects.  Dr.  Youmans's  work  exhibits 
the  value  of  such  collections  in  a  very  striking  mannei-,  and  we  earnestly 
hope  his  excellent  example  may  be  followed  in  other  branches  of  science." 
American,  Journal  of  Science. " 


New  York :   D.   APPLETON   &   CO..    1,  3.  &  5  Bond  Street. 


D.  APPLETON  &  CO/S  PUBLIOAl fONS. 

ALEXANDER  BAIN'S  WORKS. 
THE  SENSES  AND  THE  INTELLECT.  8vo.  Cloth,  $5.00. 
The  object  of  this  treatise  is  to  give  a  full  and  systematic  account  of  two 
principal  divisions  of  the  science  of  mind— the  senses  and  the  intellect.  The 
value  of  the  third  edition  of  the  work  is  greatly  enhanced  by  an  account  of  the 
psychology  of  Aristotle,  which  has  been  contributed  by  Mr.  Grote. 

THE  EMOTIONS  AND  THE  WILL.     8vo.     Cloth,  $5.00. 

The  present  publication  is  a  sequel  to  the  former  one  on  "The  Senses  and  the 
Intellect,''  and  completes  a  systematic  exposition  of  the  human  mind. 

MIND  AND   BODY.     Theories  of  their  Relations.     12mo.     Cloth, 
$1.50. 
"A  forcible  statement  of  the  connection  between  mind  and  body,  studying 
their  subtile  iuterworliings  by  the  light  of  the  most  recent  physiological  investi- 
gations."— Christian  Register. 

EDUCATION  AS  A  SCIENCE.     12mo.     Cloth,  Sl.'ZS. 

ON   TEACHING   ENGLISH.     With   Detailed  Examples  and  an 
Inquiry  into  the  Definition  of  Poetry.     12mo.     Cloth,  $1.25. 

PRACTICAL  ESSAYS.     12mo.     Cloth,  $1.50. 


Dr.   H.   ALLEYNE    NICHOLSON'S    WORKS. 

MANUAL  OF  ZOOLOGY,  for  the  Use  of  Students,  with  a  Gen- 
eral Introduction  to  the  Principles  of  Zoology.  Second  edition. 
Revised  and  enlarged,  with  243  Woodcuts.     12mo.     Cloth,  $2.50. 

THE    ANCIENT    LIFE-HISTORY    OF    THE     EARTH. 

A  Comprehensive  Outline  of  the  Principles  and  Leading  Facts  of 

Palseontological  Science.  12mo.  Cloth,  $2.00. 
"  A  work  by  a  master  in  the  science  who  understands  the  significance  of  every 
phenomenon  which  he  records,  and  knows  how  to  make  it  reveal  its  lessons.  Ab 
regards  its  value  there  can  scarcely  exist  two  opinions.  As  a  text-book  of  the 
historical  phase  of  palaeontology  it  will  be  indispensable  to  students,  whether 
epecially  pursuing  geology  or  biology  ;  and  without  it  no  man  who  aspires  even  to 
an  outline  knowledge  of  natural  science  can  deem  his  library  complete."— TA^ 
Quarterly  Journal  of  Science. 


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